umm, no you weren't mistaken -- i did say that. I do have 2 such hot-rocks - but these have not been in her viv.
But I kinda took peoples advice and instead just raised the night time temp with an infra-red light - I dont have any non-light heat emmitters or moon-light bulbs.

keep us posted. i have read and heard several sources that say lights of any kind at night can and most likely screw up there sleep. they prefer it to be pitch black. have you thought about one of the heat emitters with no light?
its a great idea to keep it a bit warmer at night expecially if you suspect respitory infection. i would shoot for 80F at night and stay away from anything under 75F. they can go as low as 70F but most prefer 75-80F.