How does Rand now make it plain that Eddie Willer's cafeteria friend has been using him to spy on Dagny?

Eddie is late and when he arrives the man is there and the ashtray is filled with cigarette butts with the $ sign trademark. When Eddie tells him that Dagny is headed for Utah to prevent Quentin Daniels from quitting his work on the motor, the man departs quickly as though he needs to find Quentin before Dagny does