How did I do this shadow?

[jimhanus]

Was playing around with .png images and stuck a shadow on this cat. Somehow I'm able to distort the shadow only without moving it entirely. The cat shadow appears to be anchored at the paws and I can distort it as needed. The thing is, I don't know how I did it! Taking the same image again and adding a shadow allows me to only move the entire shadow around but it stays the same shape as the cat image, and I can't distort the shadow. Can someone explain what I may have done differently to only distort the shadow?

catshadow.xar