i just got a new 480w light today to replace my jerryrigged lighting I had. Same things occurring, not as bad cause I dimmed the light. The way these plants react to light is kinda funny I think
I will confess, I'm a new grower. Only 10 months under my belt.
I managed to learn (by mistake) a lesson quickly though...(I think)
If you're going to give them hell (aka, a lot of light) do it early.
If you abuse them young they get used to it
I now run 2.6kW hps in a 4x8 for flower. There's no chance the first plant I started with under a 23w cfl would have been able to handle that.
Seedlings now break ground, go under 12k Lux for a weekish, then its 30k-90k Lux before flower is over.
#1 rule though...
Consistency is the key