I think you're right. She's never done it before...her 1st hatch early summer had 5 eggs,4 hatched. I asked a friend who came over to peek at the chicks if he would look inside. It was just unfertilized.
Next hatch she had 9 eggs! 3 of her own and 5 of other hens. 7hatched. I dilly dallied about looking inside. When I did one exploded nasty stuff all over me!
This is her 3rd time.
Ive wondered if the weather or daylight hours are interupting things? The ones she broke last week seemed unfertilized, no odor, no embryo. The one from today definitely had an embryo that quit. I could smell it once I cracked the shell and by the appearance.
My best guess is the fisrt eggs were unfertilized, third quit. I sure hope to have no more excitement until I meet live healthy chicks!