Maybe he was trying to get a reaction from the cat rather than hurt the cat, but still, I don't really think that's normal from a 6 year old. He clearly knew it was wrong, and that's why he was looking to see if people were watching. My kids have both had cats at age 6 (and since birth I guess) and their behavior has always been more inconsiderate than purposefully hurtful. Like picking a cat up and running with it across the house. The cats were terrified of what "could" happen, esp. with DS who is clumsy. His "petting" could be more like smacking. I would keep a close eye on the kid...I would find it disturbing as well.
