A New York State trooper arrested an East Hampton man on Saturday night on a charge of aggravated driving while intoxicated with a child in the car, a felony. State police said Flavio E. Pena-Vallejo, 42, was drunk when he was pulled over for a traffic violation on Montauk Highway near Ocean Road in Bridgehampton a little before midnight. His 6-year-old son was in the back of his 1998 Honda Civic in a booster seat. Mr. Pena-Vallejo was taken to state police headquarters in Riverside, where he agreed to take a breath test.