SayWord, raise your lights! Personally, I think thats heat stress. Mine do that as they grow and get closer to the lights. I raise the lights, they flatten back out.
Jrod, as for our leaves turning/curling under, who knows? I doubt that it's heat, seeing as it is only affecting my lower branches/Fan leaves. I sit and really watch these things, and believe me, they move around, and will do some strange shit. I wish I could take a time lapse vid and post it. I just don't panic at the sight of a curling or sideways leaf anymore. Most of what you see is going to be a natural movement of the plant.
Now if what you're seeing doesn't change in a day or so, then start looking at it harder.