Even if he hadn't bought a cup of coffee every day -- If he'd bought a cup of coffee two or three days a week, and was welcomed inside on other days, getting out of the car would be a good first step.
To expand on the point, it's common sense to avoid "looking suspicious." Like, pulling into a parking space, idling for several minutes, never getting out, then driving away. Every day for more than a week. Or hanging around the playground with a camera with a long lens every day. Maybe you're just a bird-watcher, but it's gonna look weird.
A lack of common sense isn't a crime, and thank God -- there would be more people in prison than out. But avoiding "weird" behavior is a good way to avoid wasting your time and that of the police. And the less "weird" you are, the more likely the cop is to let you off with a warning.
Yes, because we must avoid all behavior that might seem weird or we’ll be arrested. Must conform. Must conform. Must conform. Welcome to the new Amerika.