One of our chickens (6 year old easter egger) is behaving strangely. She has always been a more mild mannered chicken and kept to herself but recently she has seemingly been self isolating herself. All the chickens go out into the run during the day and she'll just sit in the coop all alone and stare out the window. When we let them free range they normally stay largely together as a flock, but she has been sitting alone under our canoe or hiding in the woods. I forced the issue and shut them all in the run together and locked the coop. She was very agitated by this as if she was frightened, but none of the chickens picked on her so I don't know what the deal is. After she settled down she just stands in a corner of the run with her beak in the corner like someone put her in time out. She seems particularly agitated when one of our olive eggers come near her, but I have never seen them pick on her so I don't understand this sudden change in attitude towards them. Her tail is down but other than that shows no signs of illness. And the other chickens don't try to run her off like she is sick either so doesn't seem she is sick enough (or at all) to warrant the attention of the flock. Thoughts on this odd behavior? Should I just like it play out?