Does this show trust?

I have a sheltie. We went for a walk and he started pulling just a little bit. And after a while of walking he was doing good. He wasn't pulling. So I decided to let him walk himself with the leash on. He did very well. The only thing was when we past a jogging person, car, or very loud noises I grab the leash and he starts to pull again. When we get away from the car or person hes fine. Does this show trust or respect? Should I teach him how to walk without a leash?