Pet names in a relationship

My SO and I work together!

A resent co-worker of his is also working with us.

Long story short, I have met this lady before and I know there is nothing going on but what bugs me is that they call each other babe.

Mind you this lady is single. I mentioned to my SO that I am not comfortable him calling her that; simply because I feel this kind of names should be exclusive to relationships.

I feel like why should I answer to a pet name that is given to anyone!

What do you all think? Am I being to sensitive?