I posted a few days ago that mine (16GB purchased from Staples) had the screen separation issue. It seems to have settled to being completely unnoticeable after a few days of use. I'm not calling it completely good just yet, but just normal use seems to have caused the glue to set properly.
There's still a teensy bit of separation (we're talking a tenth of a millimeter at most, thinner than my thumbnail), and occasionally I can press down on the screen (much harder than I would to use it, and when pushing the back of the case upward at the same time) and I'll get the "glue unstuck click" feel, but I cannot make any LCD distortion happen at any pressure I am comfortable applying, and I honestly have to get out a magnifying glass to see the difference between the right and left sides of the screen now. I suspect the glue just needed to settle in (and streaming a few hours of video seems to have done the trick, though I didn't feel the unit get any warmer).
So please take one 16GB unit out of the "defective" column and put it in the "perfect" column, because at this point the unit is well within any reasonable expectation of manufacturing tolerance from any company - I've had much more expensive items built to far worse tolerances than this thing.