Scorpio Woman Acting Passive Agressive After Rejection

So this Scorpio girl and I have been flirting in class. She asked if I like her and if we’re together, and I told her I’m not looking for anything serious. She took it very well and we continue talking for the class, but now she throws sarcastic comments at me in the middle of conversations. They seem pretty hurtful and “out of left field’.

That said, I’m pretty shy so I don’t know if she mistakes that for coldness or anything.