First off, I don't think the culture in question is snapchat. Theater kids in general have unique subcultures, let alone other demographics like regional and age based cultures. The general rule, though, is that the safest bet is often to match energy. If she sent a silly selfie, it's often reasonable to interpret you can do the same.
Trying to interpret patterns and signs can lead to creating meaning when there isn't any. That can lead to spiraling. When in doubt, match.