Gotcha, dont let it get you down too much, this happens from time to time. Doubt it had anything to do with your incubation.

Although, after our first year of incubating on perlite (we had 4 eggs not make it) we switched to Superhatch and now we had a 100% hatch rate last year. The problem with all the other mediums in my opinion is that you can't visually inspect the moisture content, Superhatch works wonders for knowing visually when to add more water. So yeah, we lost alot of eggs and one like you did due to humidity but I'm not sure if this case is due to humidity or not.