I have an Australorp hen that has decided to sit on eggs. She isn't broody...at least I don't think she is. She follows the other hens around until they have an egg and then pushes them off so she can sit on it. She only sits for a few minutes before getting up and walking away. She also builds nests and steals things to put in it. She's still in isolation (I've only had her about 12 days). What is her deal? Is she going to go broody or is this normal? None of the other three do this.