Cat Fight--Keep Out!

OK--a bit of complaining.  A mom telephoned to let me know about an incident at school.  Specifics are not important; it was petty "kid stuff" that children need to figure out on their own.  Honestly, I would be thankful if someone was forthright to inform me if my child is misbehaving; however, this call just irritated me.  In short, the woman's child believed my daughter took something of hers.  The child asked my daughter, who  in turn told her she did not take a missing item.  I reiterated to the mother that my daughter told me she didn't take this item, and I have no reason to believe different.  (This daughter is very honest--though I know my own children are not perfect). 

The mother proceeded to tell me about issues w/ another girl and her daughter dating back a couple of years.  After about five seconds of this, I said that I was sorry this was occurring, but how does this concern me or my daughter.  I don't get in the middle of my children's fights.  She tried again, but I again repeated that I wasn't sure at this point how this concerned my daughter.  I just think parents should let their children work out smaller, day-to-day issues.  How will they learn conflict resolution if their parents are micro-managing every part of their lives?