A tire will often pick up a nail, causing a slow leak that's not apparent until much later . The nail will partially seal the hole and you won't notice the air leak until you come back to get your bike out of the storage room. Not vandalism so no need to piss off the maintenance guys.
What size tires do YOU have on your bike? Slow leak from a nail in a car tire, OK. But I have NEVER had a SLOW leak on a bicycle tire from a nail.
I once even had a nail go through the tire, tube and rim.