why is my mommy dog whining while in cage with pups?

[Cyn]

So its not all the time but she does whine when she's in the pin with her puppies sometimes then shell jump out of her pin and take her toy and run around whining? So iwe play fetch a few times then she wants back in her pin with the puppies? I was just wondering if she's getting tired of being in the pin so long with them or if anyone knows why this is? The puppies don't whine unless they can't get to their mommy, there only 3 days old