Is it time or should I be worried?

Husband went to put our 5 Plymouth Rocks up and one would not come out from under a trailer they like to go to and seem to act kinda skittish. The other 4 happily followed him to their coop (he give thems grapes as treats). He left her there and came back about an hour later and coaxed her to come out. They usually go to their food and water when they go in at night. All did but her. He said she was acting fine by the time he walked away but he still didn't see her eat or drink anything. They are 15.5 weeks old. Could she be getting ready to lay or maybe she has under the trailer? I"m going to have go out with a flashlight and look if so. I noticed their nesting boxes have had a lot of activity in them too.

My dog was out there for a little while but I'm 99.999% sure she hasn't messed with her. If it wasn't that .001% then could it be time?