Same problem here, but my cluster of stuck pixels showed up suddenly about two weeks ago (I've had my MBPr since September). I took it to the Apple Store right away and the Genius gave me a very hard time. First he claimed it was "just one pixel", then when I pulled a magnifying glass and showed him a macro photo, he changed his mind and decided that "the irregularity" was "within spec"... and when I asked what the criteria were, he gave me the most BS, invented-on-the-spot answer I've ever heard from an adult. "I can't tell you that, it's not public knowledge. It's very technical and mathematical, and factors in a lot of criteria."
I had to argue before he agreed to replace the screen, and then insisted that he was doing me a favor and that they wouldn't ever replace the screen again for "this issue". *sigh* This is the third time I've argued with Apple over bunk, defective screens (once for vanity-level light leakage on my iPad 2, and now twice for major defects in my MBPr screen), and it's gotten very old.
FYI, here is the cluster. If you divided the screen into 3 columns, it's on the line between the second and third columns, right smack in the middle of the screen. It's like a piece of fuzz has landed on the screen and won't go away.
FYI, I've trued UDPixel and JSScreenFix to no avail, as well as the tapping and massaging techniques. No dice.
I'm under tight deadlines and can't be without my computer for a week, so I'll have to take it back at the end of January to have the screen replaced. Still... it's been a huge pain in the butt.