This is not an uncommon occurrence at all. I used to enjoy playing and going to shows at this local cafe/venue that was all independent musicians playing their own songs. Then they were essentially forced to shut down because they were tiny and couldn't afford the overhead with the licensing for things that weren't even. And yes, they have agents that go around to small places like this, check if music is being played and then cross reference if they don't have a license. It's like a Mafia protection racket. You are forced to pay them when they don't even provide a service to them, lest you be sued out of existence.