Curls his tail?

I rescued a rat a few days ago and I've noticed something odd about him. He curls his tail a lot. Even when I had him outside of his cage, free to roam the bathroom. I dont have any pictures of him, so yay paint program.



I've never seen a rat do this before, so I thought it was maybe he grew up in a small cage? I don't know what kind of cage he lived in originally.