Footprints

How very Fortean...

Outside the office where I work, there are three elevators. There are a set of five perfectly clear white footprints (probably plaster dust) on the carpet, leading precisely from one set of elevator doors to the next, in a steady gait. Whoever it was, they stepped out of one lift and walked immediately into the next, without pausing or stopping or diverting in any way at all.

What are the chances that two lifts would be open on the same floor at the same time? I think it more likely that the footprints came from somebody who simply walked through the metal doors and floated down the elevator shaft.