Does she have a crush on me?

One of my female colleagues enjoys socializing and laughing with others at work and a few times she has been a little teasing/jokeful towards me when I'm around with them. When she's alone with me however she acts more reserved and doesn't seem as cheerful as she usually is when I talk to her.

I'm not aware that I have ever been disrespectful towards her, just professional talk and occasionally chit-chats. I've been working at this job for only a couple of months so it might be too early for me to judge if she really has a crush on me or if she just doesn't feel close enough to treat me like somebody she enjoys approaching and joking with. And yes, I do have a crush on her myself a little bit but haven't expressed my real interest to her. I'm 25 and she's 28.

Does she have a crush on me?
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