How Does Bill Know Mike Hasn't Been Moving On?

Now as we jump to the scne where Tina is shocked at the cardboard monsters and where Mike is trying to explain, Tina drives off. This is where Bill explains to Cam that Mike hasn't been moving on, hence why Tina hates him. But he is only to be interuppted by Mike, who screams "Do you mind?!" So is it true that Bill knows Mike hasn't been moving on?