Cabin key

How do we know that this is a key to Hagrid's cabin? Pottermore merely identifies it as "Key". As Hagrid is Keeper of Keys and Grounds, it could hypothetically be for just about anything at Hogwarts, couldn't it? Or maybe it's not even Hagrid's key at all. Maybe Dumbledore, Malfoy, or Fudge accidentally dropped a key. Is this even article-worthy? -- 1337star (Drop me a line!) 23:19, November 21, 2012 (UTC)