Our cats also chew on flowers in vases, and houseplants, whenever they think they can get away with it. And some cats will eat grass, the way many dogs do. I suspect our cats do this just to make themselves vomit on the floor during the night. And they do it right where I step in it with my bare feet in the morning. That really makes it hard for me to pretend I didn't see it so I can avoid cleaning it up.
Some cats continue to try to nurse well into their adult lives.
They will nurse on clothing or other objects, and sometimes try to nurse on the family dog. And sometimes the family dog will tolerate it. Wool chewing is more cause for concern. Instead of just suckling, wool chewers actually chew up fabric. They prefer wool, or blends containing wool, but they may progress to other fabrics.