I'm not sure about this situation but what should I think?

My teacher called on me numerous times on the wrong questions lately. It has made me look bad because he calls me on questions IDK the answer to. He is trying to help me understand the subject but I just wish he didn't call me on the questions IDK the answer to. I am not dumb I answer a lot of questions but he has been calling me on bad situations. One of the times I answered "I had trouble finding that one." I know a boy said something under his breath but I'm not sure what it is. But it was loud enough to make me turn my head in his direction and everyone else's also. It made my teacher even say shhh to him and a couple kids who were talking after what he said. It may be in my imagination but I think he said, "Thats not all you have trouble with." I don't even know the kid and he doesn't even know me. Hell i can even care less what he thinks bout me. But Im not happy that if this is true and he said that, I'm mad that he said in front of the cl. If he was man enough he would say it to my face. Like I said if this is true, do you think this is messed up what he said?