Have you ever been called out for a behavior or habit that you were not aware you were doing?

I wasn't having the greatest day yesterday and was in a queue apparently having a conversation with myself. When the woman in front of me turned around and asked if I was okay I caught myself on the tail end of mumbling about what I needed to get done before I go home. I just said sorry and she smiled and then the awkwardness set in as I wondered if I had been talking about anything else.