I started to use catnip on my cat for the first time today. I put some catnip on the rug where he likes to nap. At first he tried to eat the catnip, then he would roll around in it. This went on for about half an hour. If I made any sound the cat would come two feet off the ground. But would go right back rolling around in the stuff. Is my cat OK? Did I use much catnip in the first?