Brad was really spot on with most 6 year olds when he was. Don't worry about it though. Your doing good
When me and my younger brother were 13, and 9-10, (which is close enough to Jack or Brad), he seemed like he was testing his limits a lot more. When he was younger, he was "UN"-intentionally being annoying, but he really just looked up to me. But as he got older, he got more friends, and it seemed like it was a competition, because he was trying to impress his friends, and he now had other (probably nicer) people to be around. So he kinda bugged me more, and tested me (kind like Brad just did at the end of your post lol)