To start my chickens are roughly 13 weeks old. I have a barred rock hen and rooster and the hen never wants to leave the coop. She never had problems leaving the coop before, she would leave in the morning with the rest of them. The past 3 or 4 days though she has stayed inside and won't come out... I've only seen her leave on her own once, the other times I had to motivate her. Is she sick? Is it possible her body is trying to tell her she needs to lay an egg? She's only 13 weeks so I kind of don't think that's the case but out of all my hens she is the most mature, biggest one with the most developed comb. Any ideas guys?