As has become custom these days, the police are out en masse to stop everyone who may have the misfortune of being in the wrong place at the wrong time. Holiday weekends are prime time to place DUI checkpoints at random places.
Just remember, you do not have to consent to any search. You do not have to consent to the stupid human tricks the police suggest, such as a "field sobriety test." Just say no. It's a good policy.