Do you like working there? Do you and your boss generally get along? Did you colleague elaborate? Did she mimick you / make fun of you in front of more than one person? Get your head right before you act. Consider your options. Ignore it. Report it to HR. Ask your boss about it. There are a lot of ways to handle this. Make sure you're thinking rationally and not emotionally when you decide how to proceed. All that being said, figure it out quickly and don't let it go too long.