I've been watching the threads about the glass separation problem ever since it was first mentioned here on the forum. (Even though I have a coupe).
From what I've noticed, it seems most of the complaints have been coming from those owners living in the warmer climates. That's why I think it's more of a "heat" related problem.
I'm not sure, but I'm guessing that heat may be the reason some coupe owners have experienced their headliners falling too. So it makes me wonder if it happens more to "dark" colored cars than the lighter colored ones. Simply because the darker colored cars absorbs more heat while the lighter colors reflect the suns rays.