Try swapping cars with a trusted mate for a while and see if the same guy is still following you. In my line of work we are always in close contact with the police, and like any other job, you always got the ones that abuse their authority. But up to now, I can proudly say while there is always rotten apples in the basket, 99% of the time they're just trying to do their job.

I know how it feels like, and at times being a total dickhead is the only way to deal with some people. Now I'm not saying that you are one of those people, but at times people just get carried away.

This particular officer might've had a really bad night during his first encounter with you and maybe that made a lasting impression. While we all try to be as professional as possible, there are times when the human factor kick in. And like what giddy said, Its impossible that he will spend his entire shift following you around. Some nights we can be so bloody busy there's not even time to get a drink from a servo. I can only imagine how busy the police radio can be if ours are giving out jobs every 2 minutes or less.

Just my 2 cents