Kirsten, I agree with everyone here that Lily is just being Lily. I'm thinking that maybe Luna hasn't been the most active cat and since that's what you're used to, you're unfamiliar with the craziness of a kitten that lasts even as they start growing up.

My idea was that maybe she needs another kitty buddy to play with......

(we are so evil here on PT, always trying to talk each other into getting another cat )