carpet ghost

We have this piece of carpet that's been out on the balcony since we moved in last June.  It's at the top of the stairs.  When we got home from our recent trip to my parents' house, it was in front of our front door, upside down.  We thought, "That's weird," and moved it back.  Then it kept happening again and again. 

We thought it must be out next door neighbors.  We thought the carpet must have been bothering them somehow, so they kept moving it.  But what could be bothering them about it so much?

We asked.  The neighbor said he didn't know anything about the carpet, that it's been windy, that the wind must be blowing it.  But it's been windy before, and the carpet never ended up in front of our front door upside down over and over again. 

So I said maybe it's a ghost--sounds like something a ghost might do--but why would a ghost get pissed off so suddenly?  If it's not a ghost, then who's doing it?  No one else really comes upstairs.