My eggs were in a pile too, and the top egg was already dimpled from a drop in humidity about two weeks into incubation. The whole clutch started dimpling at around day 40-42 and by day 56, when the first one pipped (not the one in the top egg), the top egg was very dimpled... much more than the others. It looked about halfway collapsed. I cut it after the first pip and the hatchling came out fine on day 59. This was all at 87.5 so yours might come out a bit earlier.