Son found a rough patch on window sill today, water damage?

Hi,

Today while doing his dusting, my son identified a rough patch on one of our window sills (photos linked below).

https://imgur.com/a/5OHuazY

The area doesn't seem wet or soft, and we don't know how long this has been like this. The home is about 3 years old, and we've had some high humidity and storms in the area over the last few weeks, but no visible water inside.

Does this look to be water damage? Maybe just the way the wood was when it was installed?

Thanks!