I have 6 layers, 3 Rhode Island Reds and 3 Plymouth Rocks. They've been together since I picked them up as one day old chicks. Just recently, one, Henrietta, has stayed away from the others. She doesn't run to the gate for treats, or any of the other behaviors they have established. She doesn't seem unhealthy in any way, and I know she is eating, as I have watched her. When I go out to collect eggs, she is just sitting by herself. Is this an indication of anything bad?