You did not click anything by accident. It tells you that you have 30 days until the service is due. It was just a coincidence that it popped up when you were fiddling with the buttons.
Ignition ON, double click and keep pressing on the button that cycles through outside temp, trip and service interval, ignition OFF, ignition ON. This all needs to happen very quick and smooth, so ON DOUBLE CLICK OFF ON. Until you hear the beep you do not let go of the button after the second click. Keep it pressed.