Girls, Why did a female co-worker look said when she thought I had left my job?

I was told by someone else, she looked sad when she thought I had left my job. She got me confused with another person who had the same name. But when she found out I didn't leave she was relieved. Her reaction was she was actually concerned and she went all reserved the moment she thought I left.
Girls, Why did a female co-worker look said when she thought I had left my job?
Post Opinion