I get more cars, okay?

Almost every evening for the past few weeks Sam and Jason have made parking garages with megablocks and then Sam drives his cars in and out of the parking garage. The past two days I also decided to build a parking garage with Sam during the day. No matter who is building, though, (whether it's Jason or I) Sam periodically will come stand next to the builder, lean in close to the builder and pat his/her back and say, "I get more cars, you build the parking garage, okay?" Then he proceeds with getting more cars and we proceed with building. I have no idea where he picked this up, but he does it whenever a parking garage is being built. Jason pointed it out to me sometime last week and I witnessed his very gentle, paternal act. Then yesterday he did it to me the first time and I felt his little hand patting my back and heard the gentle words, "You build the parking garage, I get more cars, okay?" The words really don't change much, it's always some variation on that theme. Anyway, mid-way through building the garage today I decided it was time for Matthew's nap so I left Sam downstairs and when I returned he had embellished the parking garage with all sorts of towers and spires.