Is this weird?

I think that my behavior and personality is GREATLY influenced by those people who are around me. For instance, when a cowrker of mine joined I went from kind of quiet to uber-chatty and joker and outgoing, like she was, very quickly. I was drawn to her personality. Now she has gone, I do not act that way. Is this bad and is there omething wrong with me? Or is this normal and am I making a big deal out of nothing? The more I think about it, the more I realise that I have done this my whole life. Any ideas would be appreciated!!