Anyone able to see dead/stuck pixels on Retina MBP?

Yes it's possible.

I would imagine that since it's a brand new screen and an expensive product that they're probably checking them pretty well as they come off the assembly line, but dead/stuck pixels could of course still slip through.

Yes, it is possible. Even with much smaller pixels.

Remember, separable acuity is not the same perceptible acuity.

Stuck pixels will be very obvious on a black back ground. My IBM T221 (3840x2400 @ 22.2 inch) is only slightly larger pixels (204 PPI vs 220 PPI) and I can see the 5 or 6 stuck pixels no problem on that. I don't really notice them under normal circumstances though.