This happens almost every day with my broody. When my broody Homicidal Mama gets up to stretch another hen hopes in to lay for the cause. She comes back and her box is occupied she settles down in a different box. The one leaves the box but HM does not move. I candled them tonight and they are developing nicely. She is on day 10.
Also the eggs in my incubator started out under a young broody and she abandoned the clutch after a few days and they were left unattended over night in temps in the mid 40's and they have started to hatch today.
I would guess your eggs are fine.
I hope so too. Keeping finger and toes crossed.