I had the same problem with mine. I brought it in to the Apple store and they replaced mine and explained what the problem was. It's actually very common:
The rMBP is so thin that the screen shuts to the base with almost no space between the screen and the base. What happens is that if there's, a grain of sand for example, it can break through the screen and cause a dead pixel. It's a design issue that's insanely difficult to prevent since a screen cover could make it worse by making even less space between the display and base.
You will notice that all of the dead pixels are located where your keyboard is not. So all of the pixels are in the upper-horizontal of the screen. Since that will have the highest chance of having a piece of hard grains.
Hope your problem is what I'm describing.
I can confirm your claim in my case. Two days ago I noticed a dead pixel on my Retina. When I touched it with my firger I could feel a very tiny granule stuck to the screen. Much smaller than a grain of sand or sugar but still detectable with my finger. I managed to remove it but the pixel is dead - about 1/3 of the way from the top of the display.
i had a similar dead pixel problem with a mbpro 15' retina display after owning the machine for about 10 months or so. the problem area was top right quadrant of the display.
anyway i'm writing because i'm generally the first to complain about these things, which i think i might have somewhere else around this forum. i knew i had to take the machine down to the store and to be honest was expecting to be given the right royal run around - be blamed for the problem by apple etc.
i need to mention i am fanatical about the cleanliness of the machine because i cannot stand the slightest dust on the keyboard or monitor at any time, due to doing a lot of developing on it etc.
anyway, cut a long story short, i live in sydney cbd and the closest apple store is the big one over on king and george streets so that's where i took the machine.
the service i received from apple was absolutely brilliant. i was cynical upon entering the store but left really impressed. In my case the display was replaced. I left the machine with them on a thursday and it was ready for pick up monday. all issues fully resolved. every step of the support & service process was outstanding and possibly the best I have ever received anywhere for anything.
obviously I was still under warranty and this was just my experience but my suggestion would be if you are having this kind of issue take your machine down to the store as they are extremely helpful.
on a similar note I had reason to go down to the george street sydney store again this morning in relation to an iphone5 issue - the screen had popped from the case and it wasn't a good situation.
apple replaced the phone and the whole matter was resolved in about 15 minutes.
excellent outcomes from both experiences with apple store and service and support from the george street sydney store.
i would not hesitate recommending to anyone having issues with their machines or devices to go down there and see them.