You will have to ask her. We are all so different. She could have not felt well. She could have had an argument with her husband. Her mother could be dying.

Another thing that I have learned is that very little in life has anything to do with me. People react to their own stuff and not to me.

You write that she looked upset that you were in a bad mood. You interpret this that she was angry? She could have been sad. She could have felt that she wasn't helping you.