Mine does this as well, thought not to the extent yours does. I also noticed that the colder it is, the worse it is, but only for a short time. IF the inside and outside is the same temp, the roof lays out flat. its only when the inside is significantly warmer than the outside that I get the gap.
I was able to almost completely eliminate my issues by tightening the clamps, but it comes back if its all warm and I wash it, cooling the outside of the panel.
Would love to see what FR says, but I feel this is a fairly temporary problem caused by expansion/contraction due to temp differences on each side of the panel.