I have a flock of 14 hens that are all buffs. I went to pick eggs today and had one hen that would not get off the most popular laying box. I have 12 boxes, but they all try to use the same one. A few hours later I check again and she is still there. I just went and checked at 11pm and she is still there with the others roosting as normal. When I got close to her she starting pecking at me. I have a large open pen covered and a large run that stays open and they free range. None of them have ever stayed in the pen all day. Help?