This wasn't new or unusual unfortunately. Whenever he does a family show where there are a lot of kids, there is always the stray kid 'getting into things'. But it does seem to be getting worse. A lot of the time, the parents are there, they are just to caught up in their own things to be paying attention to their children. But many times, the parents see this behavior and let it continue. They think their kids are just "so cute" and isn't it great that they "aren't shy at all". "Look at little Sammy... getting right up on stage!"
Trust me, it's not cute. It's not cute at all to see small children playing around with very expensive equipment. My guess is some of these parents think it's a family friendly show, and after all... the musicians aren't complaining or saying anything. The musicians are working. They can't very well stop the show to discipline someone else's kid. They also want to get booked for more shows, so of course they will smile at your adorable child who is pulling the strings off of their $4000 guitar.
Yesterday I honestly wanted to find some of these parents and ask them... "Hey, would it be okay if tomorrow I show up at your office with my 7 kids and let them climb on your desk and play with your computer while you work? Okay, that's be great."