Rubbernecker Mother

I am officially a Rubbernecker Mother.
The other day at the store, Big Boy wanted to ride in the shopping cart that looks like a car and has steering wheels. The problem: this car had only one steering wheel. My mom was with us. She put Big Boy on the side of the car that had the steering wheel and I put Little Boy on the other side. Of course, Little Boy kept trying to touch the steering wheel and Big Boy was getting pretty mad about it. He kept pushing Little Boy's hands off the wheel, saying things like, "That's MY steering wheel, Little Boy!" or "No, Little Boy!"
I kept saying things like, "If you want to ride in this car, you have to share. Otherwise we can get a regular basket and you can ride in there."
He really doesn't like riding in regular baskets -- he prefers to walk, but only gets to walk if he's behaving.
The grabbing and pushing continued as we neared the apples. I thought it was so funny, I started digging around in my purse for my mobile phone so I could take a picture and upload it to my Facebook. Because I was so busy digging for the phone, I didn't notice Big Boy's frustration escalating until I looked up as he kneed Little Boy in the arm, knocking the arm out of the way, making way for Big Boy's knee to hit Little Boy's forehead before Little Boy's forehead hit the steering wheel.
Screaming ensued.
My mom took Little Boy out of the car and I took Big Boy. I got another cart and forced Big Boy into it, all the while speaking in a calm voice about being nice to Little Boy and sharing and terrible behavior and getting into the regular cart.
My mom walked off to another part of the store to avoid the commotion.
Big Boy continued to scream.
Finally, a man (probably a grandpa) walked by and said to Big Boy, "You don't look very happy."
That shut him up and he behaved the rest of the time.
But I have to wonder: would the kneeing have occurred if I hadn't been rubbernecking?