Long after departing from the Westin DC City Center Monday morning, I realized that the mini-bar key had fallen into my pocket when pulled out the jacket containing the room keys.

Unsure whether the hotel might need the key for that particular room, I returned to the hotel and dropped the mini-bar key at the front desk. I would feel badly if the hotel were stuck without a working key.

Does anyone by chance know whether the mini-bar keys are interchangeable, or does each room's mini-bar have an unique key?