I've seen this exact same type of problem with one of the Mid 2012 MBPr's. To my knowledge the laptop was never put in an excessive pressure situation or cleaned improperly. It seems to be a failure of the chemical compound on top of the screen after normal use. The pattern appeared very similar to Zeleny's photo above, but grew even more extreme, mimicking the location of the keyboard pretty much the width of the screen.
When taken to an Apple store, isopropyl alcohol cleaning cloths were used by a genius with the computer-portion vertically up and off the table while the screen was face up but directly against a firm surface on its logo'ed backside--basically like its normal orientation but rotated 90 degrees to put the screen horizontal. Computer powered off of course. He used pressure while rubbing and began to produce polished spots where the IPA ate through the fogged silicon dioxide and niobium pentoxide layer. A cloth dampened with IPA dry erase cleaner fluid took off the rest avoiding the necessity for a new screen. Other than a few very small areas that seem to have better adhesion than others, the screen looks great with the layer fully removed. Note, you'll get dark black residue on your cloth when bumping up against the gasket while cleaning. The screen itself doesn't tend to produce much dirt or coloring on the cloth.
The laptop was in a tropical setting which might have contributed to the haze forming as more humidity would be present on the screen and keyboard, but in general it's a very clean looking machine. This definitely does seem to be a problem with a certain batch of screens. Hopefully a more thorough method of removal will be documented.