Yeah, is that a new feature? Maybe that's what happened, that they just clicked on it to see details. Hmmm. It's a moms' night out kind of event, totally nothing involving them, but the mom hosting made it a "public" event instead of just inviting us. So maybe they weren't really interested in the "event" so much as they were just seeing what I'm up to.
Thinking about that further... if that's really how that feature works, that is super invasive! Broadcasting to your friends what you click on? Sheesh, Facebook.