My experience in a different thread (on swimming pool changing room etiquette) has been quite interesting: there seems to be a widely shared opinion that all men are creeps and there are never any innocent explanations for their behaviour.
While I completely agree that a father in a women's changing room - especially when there are older girls - is inappropriate, I can easily see how this could happen without any ulterior motive. Be it simply ignorance or lack of judgement.
I experienced the same on playgrounds: playing hide & seek with my daughter? Mothers approach my DW and tell her that "a perv" is watching the children. Playing with DD - well meaning mothers asking her whether she is ok or needs help.
AIBU to think this is a bit excessive?