It's not dead pixels that you notice; I have a hot pixel on my Retina MBP, and it's very noticeable. But Apple doesn't warranty a single hot/dead pixel.
I literally just came from my local Apple Store where I got my Retina MBP serviced for two clusters of hot pixels. The Genius had to look up the policy to see if it was covered, and came back saying that Retina MBP screens will be replaced for even a single defective pixel. We were both surprised.
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.
As others have said Apple will absolutely replace the screen for any dead pixels. I had mine first crappy LG screen replaced because of two dead pixels and they told me they'd do it if it was only one.