How long after an officer sees me commit a traffic violation can they pull me over?

I was turning and the pedestrian hadn't completely crossed the street yet. A motorcycle cop saw it and looked like he was coming after me, but his light didn't turn before I got on the freeway. I have to go back to that area in a few hours, and my question is can he bust me if still on duty and he recognizes me? Our because he lost sight of me he can't? What's the rule here