RE: I'm a daddy, leopard geckos just hatched!! (DUW!!)
In all seriousness, the temperature based sexing, I think, and this is purely speculation, is that it takes more heat, or "cooking", to produce a male normally. There is an old biological theory that in most species, all animals are inherently female, and in more basic classes & orders, that concept would be more prominent. Just a thought, I have no evidence to confirm it, just makes sense to me.
And I've had quite a few more hatch out since. The last two hatched on the 10th. Looking at two more to hatch in the next week.