If you're in a world with Local Multiplayer Server disabled, locking and unlocking your iDevice will cause the game to say "<server> This server has restarted!" even though the server was never on. Local Multiplayer Server will still be disabled, even after saying that the server was restarted. I'm not sure if the server appears on other devices world list, even though it's disabled on my iDevice, and I'm not sure if this is a duplicate of another thread. But I did notice this. It's not a bug, but more of an annoyance.