This seems odd to us, our kitten fetches. 

We have a springer that is constantly chasing balls, and carrying things around.

A few weeks ago, I noticed the cat would take its small catnip ball up the stairs, and then drop it on the wood runner, let it go flying down the stairs, chase it, go back up the stairs & repeat.  It takes the time to ensure she gets it right on the runner..ie, works at it.

Then, we noticed if we threw the ball, she would chase it, and sometimes, bring it back.