Sorry, but I had to laugh at your post - "ball envy".
Not sure, but can the "residual swimmers" be giving him a little testosterone charge, one last "hurrah" as it were? It is more likely a dominance thing. I'm sure someone will be posting with a better suggestion, but I think you need to get him off of you, give him a firm "No" or "Off", whichever you prefer. If he persists, put him in a "down" when you take him off. Make sure he knows you're the Alpha in that relationship. Some might suggest squirting him with a spray bottle, or shaking a tin can with some pennies in it. I can't remember from your previous posts - is he going to obedience school yet? Good luck!