I scratch your back, you scratch mine

I love to have my back tickle-scratched. When I was younger, my sisters and I would scratch each other's backs in church. Even now, when I go with my dad, I try to get him to scratch my back.
My husband does not like his back tickle-scratched and he's not very willing to tickle-scratch mine. So I've been working on teaching Franklin about the joy of back scratching. My husband and I have joked, from the moment that Franklin was born, we were going to pay him an allowance just for tickle-scratching my back and massaging my feet.
Last night I was laying in bed with Franklin and asked him to scratch my back. He said, "No mom, you scratch my back." See, he has learned to love the back scratch already.
After a two-minute back scratch I told him I was done and it was time for him to go to sleep. To which he replied, "Mom, let me scratch your back." I wondered if this was really happening. Has he really learned the concept of switching back and forth?
I rolled over and let him scratch my back. He did so for, literally, two seconds. And it was like a feather scratching me. I barely felt it. Then he rolled over and said,"Mom you scratch my back."
Well, that answered my question. No he has not grasped the concept fully of taking turns scratching and being scratched. I think him scratching my back for two seconds was just a delay tactic, which he HAS perfected. He'll do anything to stay up longer, even if it's scratch his mom's back for two seconds. At that rate, he's never going to get an allowance...