Nope, just watched the Thanksgiving special.

Those are sad times when the new generation doesn't intimately know about the Peanuts anymore.

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.

Peppermint Patty is a character in the Peanuts comic strip, there are probably only 4 characters in the strip that if you say someone is like that character it would be taken as disrespectful.

I don't think Peppermint Patty is disrespectful personally.