How to get this girl to grind with me?

The first dance that my date and I went to for prom was on saturday, but shes from a different school so my prom night was on saturday and her's is this next saturday. At my prom dance (this last saturday) my date started grinding on me and I was a little bit too uptight about it and kinda told her to stop. The thing is I liked it but dont really know how to tell her i want to grind again when her dance comes up. If I tell her i liked it i think it would make me sound like a pervert so how could I say i liked grinding in a discreet way? Thanks!