Let someone go first

The other day at the grocery store I was waiting to be helped at the prepared food counter. When the clerk turned around to help customers, she looked between me and another lady to see who was first. I was, but the other woman said she only had a question. I told her to go ahead. Her question turned out to be slightly complicated, and it turned out that she was at the wrong counter, but she smiled and thanked me for letting her go ahead of me, and it didn't cost me a thing except a few minutes to be be kind.