He may be reffereing to light bleaching, which is heat related. Those flouros are probably putting out a maximum of 2000 lumens. They should run very cool. My metal halide pushes out 50,000 lumens for two plants and IMO it's still not enough. Make sure you are keeping them about 2" away from the top of your plants, they can handle it, trust me. Just keep a fan blowing air between the lights and the plant to remove any heat and strengthen the stems.
Like I said, I would wait till they bounce back a little so they can handle another transplant without stressing them to death. Once they get to that point, transplant into some better soil, without time released ferts.
...my 2 cents