I guess it would depend on how the day is going overall. If he's really riding you and it's part of an overall pattern of harassment and intimidation, file away. If he was just not paying attention and bumped into you, no harm no foul.
I've had my share of 3 day rides, they always started out confrontational and ended with me being told what a good job I was doing. They never bother locking me in because my sporh always goes down during the ride. Funny how that works