She was mean to me ..need advice?

When i was fliddling with my microscope, I saw my professor smirking at me, she knows i like her. I raised my hand to ask her a question, but she told me to ask my lab partner b/c she already explained it to her. Then later on, my professor pats me on the back as a sign of reurance, but she left her hand lingering on my back for more than a minute...it felt creepy. My lab partner and i were talking smack about her and i think my professor heard us. Now my prof is acting mean to me..but it's not like i was dissing her in front of her face. It was my lab partner, who istinigated it. Why is my prof mean to me and does she like me?