no, our broody left her eggs on day 3 returning to her high nest which was empty after we moved her and the eggs low. she had been off them at least 4 hrs and the eggs felt cold,
on another occasion in the final week she was running outside and i checked the eggs, just by resting my hand on them, and they felt extremely hot, the chicken is its own humidity machine it will sort that out so i dont think opening the nest box to look hurts at all, surely your hen isnt locked in and has access to come and go as she pleases? if this is the case the nestbox already has an opening. even after feeling hot and cold eggs throughout her setting, all viable eggs hatched; 5 1day, another the next, and one 4 days after the 1st, which died due to injury from all the nest activity,
we took out the last egg at this time and found it to be infertile. we think the kids had slipped in extra eggs, hence the late hatcher and the one we assumed was infertile, the one that hatched a day late was laid in the clutch on day 3 when the broody left them cold. this was our only black chick like her mum;
so really eggs are quite hardy, i did read, about our goose, that fresher eggs hatch quicker than older ones. which rings true with our black chick having 2 days shorter incubation period.
you dont know how old your eggs were, all you can do is wait, if theyre already a day late and dont hatch in a couple of days then i would worry.
note, some auto incubaters auto turn the eggs and stop turning them 2 days before hatch, please be careful taking out eggs as the chicks will be moving into hatch position , and if you do, try to return them unturned.