AIO-Girlfriend played a risky “girls’ night” game with dares and didn’t tell me

So, this Halloween weekend, there are a bunch of off-campus parties happening. My girlfriend and I plan to go out together in a couples costume tonight, but yesterday night we went out separately. I knew she was going out with her friends, and I was totally cool with that—I don’t really care what she wears or who she’s with (I even bought both of her costumes). To me, that’s just basic respect and trust.

Initially, I wasn’t planning to go out, but last-minute, my friends decided to hit a party. I figured, why not? So, I mentioned to my girlfriend that I might run into her out there. She told me I “couldn’t” come with her because it was girls’ night. I explained again that I wasn’t trying to join her group, just that I might see her out, but she repeated that I wasn’t supposed to be there.

Then, about an hour before we went out, my roommate told me that my girlfriend, his girlfriend, and their friends had made a point-based game for the night. The game included dares with increasing “riskiness” as the point values got higher:

• 1 point: Talk to a guy for 10 minutes, take a picture with a guy
• 2-3 points: Twerk on a guy, get a guy’s number, kiss on the cheek
• 4-5 points: Get a hickey and other stuff I didn’t fully read

My roommate’s girlfriend told him about the game, and that’s how I found out. My girlfriend didn’t say a word to me about it. Now, I trust her and don’t think she’d do anything risky, but it bugs me that she didn’t tell me.

When I went out, I actually tried to avoid running into her. But at some point, she found me, hugged and kissed me, and made a big deal about how she “didn’t expect to see me.” She asked why I was out, and I said I wasn’t worried about what she was doing. She claimed she was just joking, and that was that.

Later, though, I saw her talking to a few guys. My roommate mentioned that one of her friends was apparently trying to warn her I was nearby, but I’m not sure if that’s true.

I feel weird about the whole thing. I don’t want to overreact, but the fact she didn’t mention the game or the dares and then seemed surprised I was out there bothers me. Am I overthinking this, or does this seem off to anyone else?