Leaves curling backwards..need help

I'm new to the artificial light camp and have a question, i'm using two cfl's that are 42w giving about about 5400 lumens total, they are the soft white and still get a lil hot...I have the cfl's about 2 inches from the top of the plants and they seem okay but some of the leaves are starting to curl downward...is the light to close, they are enclosed in a four wall mylar set up that is about 9 x 12 in...the top has a large opening about 5x12 to let the heat out so i'm pretty sure its not a heat problem...or is it?