When did Lammie grow up?

I know that kids "grow up fast," and I think I'm okay with that and getting used to it. But occasionally they surprise me. David (he's 3 - the youngest in this crazy house), is life-long friends with a fuzzy and much loved stuffed animal that we all call his Lammie (it's a lamb -- see the picture).

Of all the kids, he is the only one that has always been attached to just one special guy. Virginia and Lorraine sleep with an army of animals, Patricia an occasional one, Peter maybe with a monkey or Winnie the Pooh. But, David...man if we don't know where Lammie is at bedtime, we all go on a manhunt, searching under beds, behind couches, in the bathtub, under the table, anywhere and everywhere until he is found. When the two are re-united, David will happily holler, "Lammie!" with great joy. As he falls asleep (or even when he needs a little extra comfort) he snuggles up to his Lammie just so adorably.

So, why blog about Lammie now? For the last couple days, when he can't find him, David asks, "Where's my sheep?" I'm all for helping find him, but I just wanna know -- so exactly when did Lammie grow up and become a sheep?