Locked out of downtown underground parking!?

Went to an event in the Theater District tonight’s get and parked underground. Walked back up to street level at stairway K. When we came back every stairway door was locked! Is this normal? We had to walk all the way back to the drive-in entrance and walk in to the underground parking that way. Surely there’s an easier way to get back to your car late at night after a concert!