I adopted an adult from the shelter last Sunday. So far he seems to adjust well to his new home. He's friendly to everyone, doesn't object to being handled, and uses the litter box. I noticed that he has never meowed, and sleeps a lot (don't know if he sleeps more than the average adult cat), and is kind of lazy. When he's laying down, and I dangle a string of yarn in front of him, he will try to catch it with his front paws, but usually won't get up, or chase the string. Is this behavior normal?