S.P.
It's hard to know what's going on in a classroom based on reports from little kids, but I don't blame you for wanting to get to the bottom of it to be on the safe side. You might schedule an appointment with the principal, and tell her that you don't want to make the teacher defensive, but you do want to feel more confident about the situation. Ask her if she would mind observing in the classroom and getting back to you. That way you don't have to do it. I am always nervous about a teacher consciously or subconsciously taking their frustrations out on the child of the parent who is annoying them, which is why I suggest you ask the principal to do the observation. Let us know what happens!
S.