My apartment had a leak back in June that did enough water damage to the wood flooring that we had to replace some of the wood. We hired a flooring guy to come in and replace the damaged wood and refinish the entire room so it all looked uniform. Fast forward 9 months and the new hardwood flooring looks like its splintering along the edges. Does anyone know why this happens or how to deal with it?

Here are some pics to help illustrate the issue:

Here is a picture of the flooring that was NOT replaced. You can see that there is a negligible gap between the boards:


Here is a picture of the flooring that WAS replaced. You can see that it looks like the edges are splintering along the long end:


Zoomed in picture of the splintering between the floor boards:

The splintering that you see is really filler that has come loose as the boards have shrunk. There was a gap when the floor was finished and the filler was applied, then. Now the flooring has shrunk due to ambient humidity causing the flooring to pull away from the filler. The gap may close during more humid weather.

Thanks for the response! Is there an easy fix to this, such as replacing the filler? My concern with that option is that the color of the filler may not match the color of the finished floor.

Matching the color is the easiest thing with colored putty, it is such a small gap to fill. Use a color that matches the darker part of the grain, rather than being too light.
The hard part is matching the right gloss level with a coat of finish to match the surrounding flooring. One thing that may make everything easier is to use wax sticks, which will have a satin shine and not need a coat of finish, which putty needs or it will start to look dirty from the surface getting dusty when it dries.
Home depot has some in the paint section.

Looks more like edge bonding to me - the boards swelled after install and compression set with one another, then as the boards shrank again in the winter, pulled apart taking pieces of wood with it. From the zoomed in picture, it doesnt look like any filler was applied here. That said, a little filler now would certainly fix the problem. We like to use a siliconized caulk rather than a putty as it has both flex and staying power. Might have to go to a specialty paint or hardwood supply store to find some though.