i had the same problem a few days ago. im using a dual flor-o and on the ends its a lot warmer than the middle and the ones on the end did the same thing and urs i think u may had ur light a little to close. rule a thumb i have read was "if the top of ur hand gets wamr and hot ur to close hold it there a for a min or see how hot it is if its warm ur proly to close ur hand really shouldn't feel much heat" hopefully this helps. i move my light a lil higher and so far no more dry dead leaves..

~Strey~

p.s. what kinda light is that ur using in the picture? it looks like a incandecent growing flood light? if so those can get pretty warm...