Thanks Meter 310
Join Date: Nov 2009
Location: Long Island, NY
It's problably the oleophobic coating like others said. I have the same thing on mine, and have been thinking of exchanging it because of it. But I think I might as well keep it, as this phone has no other problems, and I'm sure it will probably wear off any phone I get with due time.
Take a paper towel and lightly go over that area. I bet it comes clean so you can't see it anymore until you wipe your oily fingers in that spot again. It seems oils like to get stuck in those spots unless you clean it with something that absorbs oils, and isn't reused over and over.