Warm Door Handles

Every morning when I arrive at work I scan my id badge which unlocks the door. Then I grab the door handle and pull it towards me, opening the door. Each and every time I grab the handle, I am surprised to find it warm, as if someone else had been holding on to it for the last five minutes and has recently released their grip so I could grab hold. There is never anyone in the lobby with me, and no evidence that someone has recently been there. The warmth is unmistakable. It is so odd to me that the handle is warm. Logic dictates that it should be cool to the touch. Or, at least, the same temperature as the room, rather than warmer. Someday I shall solve the mystery of the warm door handles.