You sure they didn't clean out the dead eggs, lay new ones, and that's what you saw hatched?With cooler weather they may take up to 8 to 10 days. I once put a frame of comb outside
not knowing that there were eggs in it. After 5 days, (3+5)=8 they still hatched inside the
hive when I put the frame back . So from 3 to 5 days they are still egg stage when temp. is cooler outside.