Do you spend your time looking at black displays? IPS display can "bloom" however my initial thought is that the display lighting is very uneven, so yes I would be speaking with Apple.
Right now I am on one of my rMBP`s, I will check my own rMB and see if it`s comparable, there is the aspect that if the issue does not impact your workflow is it a problem? Bear in mind that although Mac`s are not cheap they are mass produce and some variance is to be expected, equally I would want this to be rectified.
My own 1.2 Retina`s display is completely uniform to the eye, even at full brightness. So as bad as it is you should return your MacBook...