Bit of heat stress and probably some over nuting. get a fan in there and just give pure water for the next 2 waterings and you should be fine. She does look a bit stretched for a 600w lamp did she veg under different lights?
not to thread jack but I've been researching for a week and this is the first case I've seen that looks similar to my problem, especially the first pic, how the leaves are folding downwards.