Someone did and got away with their lie. The ID is set by the first person who enters. They probably zoned in, and zoned out very quickly when they realized their mistake. Provided no one enters while the locked person is inside, it should be fine. But you likely had a chain reaction. First guy makes mistake and enters, leaves fast enough to not get noticed, but someone else happened to be loading in at the same time. They get locked and then every player after is locked due to the first persons mistake.
Depending on your PC you can load this game extremely fast. With no addons I can load in in about 2 seconds, where someone with a full suite could take 10-15 seconds. Easily enough time to zone in and out without being noticed.