A little, teeny part of Mandy's very Ravenclaw (and very logical) brain was telling her that maybe the charm had caused her to be a bit too cheerful, but the rest of her brain was too busy feeling lovely to worry about it.
She found that she was bouncing a bit where she stood, and decided that Neville deserved a hug for making everything so fun, so she bounced over to where he was. "I'm going to hug you now!" she announced, with a grin, before wrapping her arms around him rather sloppily.