Do some girls flirt by being "mean"?

I have this coworker. She is younger than me (im 28, she is 20). Although at first she was nice, now she has turned very sarcastic and mean (in a playful way). there's nothing wrong with that, in fact I enjoy getting into these arguments with her that go on and on until other coworkers step in and say something like "kids, stop fighting". I've asked her why she is "mean" and she tells me "you'll get over it" or because I'm annoying or tells me to stop crying. I usually act normal but she finds everything I say or do unfunny or annoying (she usually says it to my face, but a lot of times she'll give me this "look" and give me a sly smile. I've never seen her act like this with anybody else and I know that some girls at that age still act "weird" around guys. I like her quite a bit, she is very mature (although she'll rely on immature stuff like shushing me when she losses an argument). Could this be flirting on her part or could she be really annoyed?
Do some girls flirt by being "mean"?
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