Hi Everyone, please forgive me if this is a basic question, I have never had hardwood floors till now.
In December I had about 1000 square feet of oak floors installed by an Amish man.
In the last few weeks I have noticed 4 or 5 spots where the boards have slightly separated from each other. The gap is very small, at most you can put your finger nail in it, but at least one of them is about 12 feet long.
Is this normal? should I be concerned?
I am afraid some dirt / dust will go in these gaps and start to make it worse.
is there anything I can or should do?

some additional info that may or may not be reliant.
I am in Minnesota, so its still winter here. The house has a good hvac system with a humidifier and maintains 70 during the day, 66 at night all year long.
The wood was delivered and acclimated to the house for 2 weeks before being installed.
The floors were sealed with poloplaz primero.
Thanks in advance and if you need more info let me know

Hardwood expands and contracts with changes in its moisture content as a result of changes in the relative humidity. It is normal for contraction (shrinkage) to occur during the winter months when the humidity is relatively low and expansion (swelling) to occur during the summer months when the humidity increases. Annual Moisture Content ranges differ by geographical location. The process is to let the floors acclimate to the Annual Average Moisture Content for installation. That way the floors will not shrink or swell excessively during seasonal changes in relative humidity. That finger nail size space will go away come spring and summer. The acclimation process is not time dependent. Did the installer use a moisture meter to check the moisture content of the floor and subfloor at the time of installation? Hardwood floors are a natural product and individual boards may behave slightly differently. Hardwood will be happiest if the house is kept within a 40/45% - 50/55% relative humidity range year round. If it goes too low in the winter you may see small gaps. Does the humidifier indicate the relative humidity in the house? If not small humidistats are not expensive and will let you monitor the humidity. Go through the seasonal changes and see how the gaps do. If the whole house is not gapping then I would not panic.
Also, if individual boards are behaving (swelling and shrinking) differently it may be due to what part of the tree the boards were cut from.

Thanks Jim!
I looked at my "weather station" and it only has outdoor humidity so I just ordered a humidity monitor for $8 on amazon.
As for the installer, he was Amish, the only "modern technology" he used was the manual nailer, he even used hand saws.
The wood was locally sourced red oak and milled by the Amish.
Humidity in upper Minnesota is low almost all year (we get 1-3 weeks of 90+ temps with high humidity in July) I have the humidifier on the furnace set to 30%, any higher than that and the door hinges and windows will start to form ice on the inside, but there is no guarantee that that is accurate so a second tester is a great idea, thanks for the suggestion.

Your installer is a rare commodity these days. Can you post a picture of the floor...would love to see his work.

Hand saw. Each Amish sect is different. My manufacturing guys use all the modern technology available except they use diesel powered generators. They wanted to use wind turbines to power the manufacturing plant during an expansion process three years ago. Turned down by local environmentalists.

Curious. What procedure did they use to sand the floor?

Realistically you have a very minor issue. Can you see it from a standing position? If not it doesn't exist, or that's what an inspector would say.

for the sanding, he had the man who drives him operate the machine, he did the edges, and stained the floor on his knees with rags. He used a roller to apply the sealer.

the gaps are only seen from a sitting position
Thank you for the input, like I originally said, I have never had wood floors so i have zero experience. It's definitely prettier and nicer than the ceramic tile and carpet that it replaced.


I will post pictures later today, I need to find a place to put them and then link to them.

Environmentalists were ok with diesel but not wind turbines?
Also, does it matter how tall the inspector is?

I'm sorry for the delay, work got the best of me then hand an emergency trip.
few updates for you.
1) photos - all the photos i took of the process are here, the first ones are the before, then i would jump to the end for the finished ones.
https://www.dropbox.com/sc/pendo3o2tfcn3ut/AABte_dFfWpoDTuTODinMYMVa
2) Humidity - you were right, the despite the humidifier on the furnace, we were sitting around 20%.
I guess it was mostly due to warmer weather so the furnace was not on enough hours.
As a temporary fix and with good timing, I boiled my maple sap in the house this year, that put about 20 gallons of water into the house over 2 days and kept the humidity at 50-70, that was about a week ago, now its down to upper 30's, but with warmer weather coming it should come up.

I spoke to the local HVAC company and I have ordered a Lennox 220v Humidifier. This is a separate unit that can turn on the fan without the heat, and blows steam directly into the plenum.

Thank you for your advice and help.

Looks beautiful from here!!!! I didn't notice the gaps....are they in the pictures? Do you keep the dogs' nails trimmed? Do you have a way to control the summer humidity.....don't want it too high.