To fly or not to fly an American flag? That was never a question for Bruce Watson, who has put his national pride on display for years — and nudges neighbors in his small New England town to do the same. “I’m very proud of our flag,” the writer said. “It’s the symbol of ‘We, the People.’” But as the polarized nation marks its 250th birthday, Watson, 72, worries his Stars and Stripes may now need an asterisk. “If we do fly the flag, we will also put out signs to make it clear that we are not