I just had a br-111 engineered wood floor glued to concrete in my home in FL.
That evening I noticed a nail head in the middle of the floor. I contacted the company and was advised the installer put the nail in to align the flooring and forgot to sink and putty over it. He called this a spring nail.
Is this a common practice ? They are willing to countersink and putty or replace the board.
I appreciate your reply.

It is common to nail a few planks to get a straight line for an install. Forgetting and not covering it up is a mistake on their part though.

Mahuk, Your thinking of a "naildown installation". Even with that there's methods to avoid top nailing.

It's not common practice to nail boards on a gluedown over concrete, or if you installed a gluedown over a wood substrate for that matter. What type of nail did he use? If it has no head it's most likely a headless pin. Regardless, how are they going to countersink into concrete? Maybe it's holding down a hollow spot? Very uncommon. If they cant maybe pull it and hide it, I would take them up on replacing the board.

Totally agree with Howard on this one! Glad someone else spoke up cus the homeowner called me from FL today and thats what I told him too.

One nail head is not a big deal. Just countersink it and putty it.