Nap Time

I just had the following conversation with my son:

Daddy: "You know, I think it's time for a nap."
DS3: "No nap. I want to stay downstairs."
Daddy: "You don't want to go lay down in your bed and have a rest?"
DS3: "No, not right now. I'm busy."
Daddy: "Busy doing what?"
DS3: {glancing at 3 large piles of wooden blocks}"I'm building a train, a giraffe and an elephant."
Daddy: "Wow! I guess you are busy. But it is getting late and you probably need a nap."
DS3: "No naps! I just woke up."
Daddy: "OK, you can finish playing with your blocks, but we have to go upstairs and take a nap in 10 minutes. OK?"

He turns his attention back to the blocks. About a minute passes.

DS3: "It's getting kind of late."
Daddy: "Yes, it is."
DS3: "I think I need to take a nap."

He runs over and jumps into my arms. I take him upstairs and tuck him into bed. It just has to be his idea.... I wonder where he gets that?