I am not a parent, but I was a teacher for whatever that is worth. I do not think it would be annoying to ask, but it may not be something she is able to do in the detail you wish due to other demands. Let's say a kid does hit your son (or vice-versa), she now has to break it up, get them calmed down, watch the other kids, try to teach a lesson, and now write a note about it? Yeah, it might not happen.
Personally, I would arrange with the teacher a time to speak with her one-on-one about your concerns. Take 30 minutes or so to go over some incidents/reports from your son and see what is going on. At that time you could ask for some updates - daily, once a week, whatever the teacher can accomplish, within reason.
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