I have never seen this before, but I have heard of hand set floods (possibly caused by incorrect re-assembly)

RonMicjan has posted a proper procedure for dis-assembling and re-assembling the front cover. You have to take care to re-install with a nice even compression against the gasket protecting the electronics.

I've seen others fill their handsets with Johnsons baby oil, or you can simply dis-assemble, if you dare, to look into it further.

I have done so for other reasons, using the above procedure. No problems. You just need to find the correct hex-head screwdriver.

Good luck.

Edit: On the other hand, it doesn't look like much. I'd continue diving and keep an eye on it (as you should anyway). If/when a real problem is confirmed, you do have a couple of redundancies.