We have a neighbour like that, curtain twitcher that just makes a fool of herself trying to play neighbourhood watch but really does nothing more than make a pest of herself. I hope she doesn't bother you further, she likely just wanted to play the hero/martyr, the note serving to draw attention to her 'good deed'. if that had been me I'd just have simply picked up the rubbish and binned it. 🤷🏻‍♂️