I've been using ours, even if they've been out overnight. When the eggs come out they're toasty warm, and our coop doesn't get much below freezing (if at all) since we have a lightbulb in it for heat. I think it'd take a while to freeze through (and you'd likely see cracks in the shell if that happened, since there's less air space in a fresh egg.
The internet (wikianswers) claims that eggs freeze at -10C, which is 14F - just about the low last night. So if they were in the coop, they probably didn't get that low.
If they did freeze, or if you think they did, I'd use them more quickly. If you want to freeze eggs for storage, these would probably be prime candidates, since they're halfway there (at least) - here are some instructions for freezing eggs and dealing with them once they're thawed
Raw eggs can be frozen. To freeze whole eggs beat them just until blended. Pour them into a freezer container, seal tightly, label with the number of eggs and the date, and freeze. Substitute 3 tbsp (45 mL) thawed whole eggs for 1 large fresh egg. Eggs should not be frozen in the shell.
Egg whites can be frozen "as is." Pour them into a freezer container, seal tightly, label with the number of egg whites and the date, and freeze. Substitute 2 tbsp (30 mL) thawed egg whites for 1 large egg.
Egg yolks will thicken or gel when frozen and therefore cannot be used in a recipe unless they receive special treatment. To prevent this gelation, beat in either 1/8 tsp (0.5 mL) salt or 1-1/2 tsp (7 mL) sugar or corn syrup per 1/4 cup (50 mL) egg yolks (about 4 yolks). Label freezer container with the number of yolks, the date and whether you added salt (for main dishes) or sugar (for desserts and baking) and freeze. Substitute 1 tbsp (15 mL) thawed yolks for 1 large fresh yolk.
Thanks, Sue and Karryn! We've been cooking and eating any possibly frozen eggs within a day or two, and they seem to be fine. The info on freezing eggs on purpose will come in very handy when the weather warms up and we get a big surplus.