Haha, I was kind of joking. But seriously, they ALWAYS foal when they think you aren't looking. Ask my friends who work on the billion dollar Thoroughbred farms on foal watch. The really expensive mares wait until you go down the road to check on mares in another barn, and then have problems. Yikes.
Is she on your farm? Heck, if she is, and you are really worried about her, do what I do. Grab your shotgun and your flashlight, call your dog(s), and trek out into the fields every couple of hours to check on her.
I have pulled many all nighters on manual foal watch. Because they also like to show every sign of imminent foaling and...not foal when I am checking. LOL Darn broodmares!