Again, I'd also like to hear advise from some other folks.

Since you ask though, I'd put a smaller bulb, like 42W cfl and about 10" up and try it again. It still sounds like a huge amount of light for a newly sprouted seedling.

If that were a clone I'd say it also could have rotted from drops of water smothering the leaves and center where the leaves start. You don't get the little plant wet and drippy when you water right? Just the soil right? Your humidity sounds good.