Duh, yes you're right, that's what I get for sitting late at the 'puter counting on my fingers, instead of getting up and looking at the calendar. The eggs I set last night should be hatching around March 9.
I did once have a hen who set for over 6 weeks, after it was apparant that after 3 weeks the first clutch wasn't going to hatch I gave her a fresh clutch of eggs to incubate. She seemed none the worse for wear after her long confinement. Actually, these past few days she's been acting as if she's ready to go broody again.
Leah, I wish your Buff O great success with this hatch! As you see, there are some production breeds who will still go broody, Buff Os are definitely one of them. My kids always think it's so funny to see the hens setting like pancakes. She may just be extra protective around onlookers and wait until no one is around before slipping off her nest(griddle).
Beau, I hope you have a happy surprise waiting when you get home. The Mamas do cluck to their egglings before they hatch, and the chicks can peep loud enough to be heard through the shell. I was so surprised the first time I heard it, I thought the chicks must have hatched already, and was so surprised to find the eggs still intact. The hens & chicks are learning the sounds of each other's voices. My hens are usually intolerant of any other chicks but their own, even if they look the same. So they must detect a difference in their chirps.
Best wishes to all the broody Mamas & their human caretakers!