Key to it all

So I'm spending a couple of nights at the guest house of a well-known institution. Return to the place after an evening meeting some folks, and there's nobody at the reception desk, nor is my key on the desk waiting to be picked up as it usually is.

I go hunting for the guy who's normally there. Find him in the kitchen. He says the key should have been on the desk. Comes up with me, confirms it isn't, then looks through the lone drawer. It isn't there either. Looks around on the floor, on a bare shelf, and there's nowhere else to look. No key.

He tells me to wait in the conference room off the reception area while he searches or tries to get a duplicate. I wait there about 20 minutes, while he tries to call people, searches the desk some more, periodically signals his lack of success to me. I'm getting more and more frazzled, I'm sweaty, I'm longing for a shower.

Suddenly I see him running towards me with a smile, waving the key. Found it. Where? Lying on the table in another guest's room.

Here's what happened. The guest picked up both his key and mine. Used his key to open his door and then stuck it in the slot that turns on the power in the room. My key, he set down on the table. When the reception guy went in there to get him some water, he saw my key lying there. "Whose key is this?" he asks the guest. "Mine", says the guest. "No it isn't", says the reception guy, and brings it out to me.

I'm unable to fathom this. Did this guest think he might slip quietly into my room and steal my surge protector while I was away? Did he seriously think my key was his, as he claimed? If so, what did he think he had used to open the door and switch on the power? Did he just make an honest mistake? If so, why didn't he consider returning the key to the front desk and saving another guest substantial bother?