Rocking the kid

At the back entrance of a great bookstore. The parking lot is packed because of the reading going on: Jonathan Lethem on his new book. A collection of essays. I listened for a while and left unimpressed while he is still talking. About himself mostly.
My car is tucked into a corner at the other end of the lot. I hurry when I see two guys almost hidden in one of the doorways. They're talking, probably on a smoke break. One of the guy is moving his arms up and down and it's only when I get closer that I can see what he is doing: trying to put to sleep a small baby, smaller than his forearm.
The kid is wide awake, his yes looking up at his dad, who cannot be more than 30 years old.
The dad is still talking to his friend, the motion of his arm regular as if he was pushing something up and down. As I reach my car and leave I notice in the rear view mirror that the kid is barefoot. It is cold.