Even after reading the Wikipedia article to find out who "Peppermint Patty" is, I don't quite understand the reference but get the impression that it may be slightly disrespectful?
Peppermint Patty´s best frient, Marcie, tends to eccentrically call her "sir", which may be due to Marcie´s bad eyesight and Patty´s slightly tomboyish behaviours. Patty at first is hugely annoyed by that, but eventually starts to accept - or better, less obviously discourages - that behaviour.
I don't think Peppermint Patty is disrespectful personally.