Oh, heavens! Don't you know? When I want to tell you what's wrong with your child or grandchild, I'm being concerned. When YOU want to tell ME what's wrong with my child or grandchild, you're being nosy!
It takes at least two people to make a situation about this. But some folks take offense, bear-like, at anything that seems remotely like criticism; some people take offense as a reaction to the chain of frustrating events that have already happened during the day; and some people just don't want to hear it.
On the other hand, to say something that sounds even remotely like fault-finding, and actually to be heard, takes skill. Even the tone of one's voice must be right, and one must choose the right words to say.
It was good that the school called you to get your side of it.
When my children were that age, I would have appreciated someone letting me know about torn clothing, if I knew the person was a friend. In fact, sometimes one of the teachers would warn me, as I was in the pick-up line, "I just want you to know in advance that your son's shirt acquired a big hole this afternoon. He got it playing with the other children on the jungle gym." That told me that I'd have mending to do that evening and that it was an accident, not a catastrophe or an altercation.
So I think I might have mentioned this event to the child's teacher, but I wouldn't have talked to the family. I'd let that be the teacher's job.