I'm not at ease if I see any police car in the highway. Of course, I'm not stealing car. I guess I'm just afraid if I've done something wrong like not wearing a seat belt. Do you feel nervous when you see police patrol cars at your back?
It seems like a normal instinct to be a little bit not at ease when seeing a police car. But, most likely you have absolutely nothing to worry about. Or at least, that's what I tell myself.