That is the problem with facebook --- it may be in the way they read your post, as this has happened to me. You might have been talking about something totally different and they thought it was about something they knew something about so they took it the wrong way-- maybe you could clarify the point you were making once you know her objection. Unfortunately since you are in a leadership role--- your words mean more now and to many more people.
I handle it by being careful what I post on my Facebook page. The desire to "post what you want" is understandable, but by being part of the PTO you've become a leader, and like it or not, leaders are scrutinized.
It's curious that you say nothing was said bad, yet someone found it inappropriate. It's possible they misread it or are overly sensitive, but is it also possible that you could have written your post more carefully to avoid misunderstandings?
I was wondering if you've ever posted something on your fb page and someone at the school caught wind of it and said it wasn't approiate. Mind you it was MY fb page and nothing was said bad. How do u handle being part or the PTO and being able to post what you want on your Fb page? Thanks so much.
