I had an issue with a single dead pixel on a 3 month of rMBP earlier this year and Apple replaced it (the whole machine!) without any fuss. The Apple tech guy said (and this is pretty much the exact quote) "the rMBP is all about the screen, a dead pixel is not acceptable". Say what you will about Apple but their support is the best I have ever experienced. If I were you I would book an appointment at an Apple Store and get it fixed. I doubt you will have any problems. Backup everything first and be prepared to do a wipe and get a new machine if that isn't too inconvenient.