Why is V's arm darker?

[Mathroy]

I'm playing Female V, and now for some reason her right arm is just darker than the rest of her body. I have the Gorilla Arms, don't think it matters though. It just really looks like a bug, but reloading the save or restarting the game doesn't fix it.
Has anybody else seen this before?

[m662]

If you are not running any mods that affect lighting or skin color I would suggest try to replace the gorilla arms with cheap mantis blades or other replacement than exit vendor so it updates appearance and go back to the vendor and select gorilla arms.

If that does not solve it try to reset all graphic options and if that fails try verify files on steam. Though in this particular case I have doubts the last suggestion will have impact. Nevertheless it is worth a try.