Secret Society Glitch?

My sim left mint chocolate chip ice cream at the Britechester statue her last term at University. One member showed up the next night outside the house but nothing happened. Now that my sim is graduated, two members show up almost nightly around midnight. They walk into my sims house, wake her up, wave, and then go about their business.

She was never asked to join so I'm confused. If she is somehow already a member, do they show up every night like this? Not a fan if that's the case.