6 year old being “fast”

So recently my sons father said that I needed to “watch” my 6 year old, who just turned 6, because she was becoming fast. I asked what he meant by that and got very upset and said he’s already told me and I needed to fix it! It went back and forth and then he said that there was a time where he was watching her and our son and she was “popping” her butt, twerking I’m assuming he means and looking at him. I said was trying to see if you were looking and if she would get in trouble and he said no because she’s smart and knows how to not get caught. Well all of this rubbed me the wrong way and I’m no longer comfortable with him being around. Today he was over and as he was leaving he called me from outside to say she was sitting on the couch with her legs open and looking at him. She had on biker shorts and he had to walk in front of her to leave. Am I crazy for thinking he is delusional or should I be worried about something else? I don’t for the least bit believe my daughter is looking at him in any way, she honestly doesn’t care too much for him, which is another issue, but this is the only time and person I’ve heard any type of comments like this about her. Please let me know am I trying to defend my daughter and I’m in the wrong