I had a curious experience

yesterday and I am still not sure what to make of it.
I was stopped by the police. No, I was not doing anything wrong. As far as I know the two cars coming up the street behind me were not doing anything wrong either. We were all just stopped.
We sat there. I was in the sun. I went to move into the shade. I was told not to move.  One of the cars behind me attempted to reverse and go another way. He was stopped from doing that as well.
The two policemen seemed quite relaxed. They went back to their air-conditioned vehicle (and drank water). They had a conversation and I saw one of them using a phone. They sat there for a bit longer.
Some traffic went around the corner ahead of me in what appeared to be a perfectly normal fashion. There was no visible emergency services vehicle or police escort.
After some minutes one of the policemen got out of the car and waved me on. He waved the two cars on.
I went home feeling annoyed - to put it mildly. Should I put in a complaint? I was debating this when I had a phone call. It was not from the police with an apology but from the secretary of the owner of one of the cars. He had described the incident to her and she had recognised me from the description "on a tricycle wearing a helmet which looked a bit different".
She told me, "He is dealing with it."
I will not put in a complaint. He knows who I am and I know who he is although we do not know each other. I am sure he can deal with the situation. If they had no good reason to stop us it will not be pleasant.
But, it was curious.