closing doors that are already closed

[drioles]

No: HPFGUIDX 70136

  I was just wondering if anyone caught the instance in chapter nine when Harry has just learned that Hermione and Ron are prefects and Harry is upset.  Hermione asks to borrow Hedwig.  Harry is packing and stays bent over his trunk until she leaves.  He hears the door close and can only hear the sniggering of the empty portrait and thewastepaper basket coughing up owl droppings.  He turns around to see that they are gone and hurries over to close the door.  Wasn't thedoor already closed?  If so, who opened it? Could it be the same source of all the cool breezes and prickly feelings Harry gets now and then?  Could it have been Kreacher?  Someone else following Harry around?