I've had eggs partially dehydrate before to the point of dimpling in half way through incubation and then go on to hatch perfectly normal babies. Drying out may have been a contributing factor but I wouldn't say it was definitive. When I've had problems like this in the past myself (and I could pinpoint an actual cause) it was usually due to temperature spikes. I keep a digital thermometer with a min/max memory function in my incubator so I can track instances like this.

I'm very sorry for your loses, but don't beat yourself up over it. Everyone who breeds long enough will eventually have this happen to them and most of the time you'll never know the cause. I hope you have better luck with your next clutches.