She was not herself

"She didn't seem herself." / "She wasn't her usual self." / "She wasn't quite herself." All of these mean she was behaving in a way that was unusual for her character. "She seemed distracted." (if she wasn't paying attention and that was not usual for her or inappropriate for the situation)

Could be unfriendly, rude, distracted. It means you are talking to someone you know but they seem to be thinking about something else or upset with you in some way.