Now, I'm contemplating getting the vet back out. She's overdue and we have people waiting on the foal. [QUOTE]
This is why she hasn't had it yet.
Here is what you do.... Make a bunch of ruckus around the barn like you are packing to go on a trip or to a show. Make sure to talk real loud how you will be away for at least a whole day, if not two and how no one
will around so the mamma had better not have her baby while you are away.
Throw some tack in the car/truck, toss in an overnight bag, lock up the house and barn and get in to your car/truck. Then slowly drive out the driveway lamenting out the open window how you sure hope she waits until you return to deliver the foal.
Go park at a neighbor's house then sneak home and spy on her. Sure 'nuf, she will have her baby.
It's written in the code book every horse is given as a foal on how to fool humans and give them grey hair.
Seriously though, the vet's estimate was just that, especially since it sounds like the breeding wasn't witnessed. Call the vet out again for sure, but chances are everything is ok.