All three, or sometimes only two, of my 15-week Golden Comet Pullets will sit on the roof of their coop at night instead of going inside, even if it is very dark outside. When I try to put them in the coop, they fluff up and squawk. Thy don't jump up on the roost, like they used to before, they just stand there. I have heard that this is a sign they will start to lay soon, but this might just be an old wive's tale. Any advice as to what and why?