My Rhode Island Red hen likes to snuggle next to my Welsummer at night. Normally, they seem fine with that arrangement. They also get along well during the day. However, recently, there have been three instances where I saw the Wellsummer peck at Red when she tries to get next to her. I also saw Red peck back once.
I'm going to check (as best I can) that we don't have red mites, and that neither hen has a injury that might be making them irritable. Can you think of anything else that I might want to check for?