It looks like it may be the issue of the antiglare coating starting to come off of the display. Someone please correct me if I'm wrong, but I think Apple has been pretty responsive to that problem as of late...
Either way, definitely time for a Genius Bar appointment!
They will at an Apple Store, yes. I had it on my 13" rMBP for a while and ignored it since it was on the non-screen parts of the border and didn't really bother me. When I bought a 15" I wanted to give the 13" to my gf in perfect condition so I took it to Apple and they turned it around in a couple of days with no charges.
If you don't have a local enough Apple Store contact Apple support directly to arrange shipping and so on.