Jordan often will meow while he digs in his litter box. It's not a regular meow, it's his aggitated meow. He meows with his mouth closed when he's irritated or when he wants something. He stops when he is actually going potty. He's been doing this for a long time & I often watch & listen to make sure he's not straining. He seems fine, but I'm wondering if anyone else has a cat that "sings" while they dig?