Yeah man, this is very suboptimal closing. "Meet & greet" sounds extremely formal and not that appealing to a girl. She's kind of poking fun at your invite the only way to respond is with humor.

"Yeah, I was hoping you could sign my left buttcheek"

It sounds to me like she's complying... I'd go along with her plan without losing the frame you're the man and is in playful control of the interaction in digits. I'd say. "Ok great, I do want your autograph... in the form of digits ;) "