I too, was wondering about the dynamics inside the coop. Is she being bullied, or maybe the rooster pestering her - what could cause her to desire being away from the others. It's too bad you can't lock her in and have a game cam or similar camera to record what goes on when the door is shut.
For my peace of mind and her life, I would get her into the coop every night.
For my peace of mind and her life, I would get her into the coop every night.