A local concert promoter has alleged that Bangor City Councilor and local bookstore owner Gibran Graham requested that he help him arrange a book-signing event with Trevor Noah at his business next month when the comedian and host of “The Daily Show” is scheduled to perform a standup routine on the Bangor waterfront. Graham’s alleged request — which he denied making — could have put him in violation of city ethics rules, as Waterfront Concerts owner Alex Gray was in the middle of negotiating with the city an extension of his company’s contract to hold concerts on the Bangor waterfront. Those rules bar public officials from using their office for personal gain or accepting favors from people with business before the city. Graham owns The Briar Patch, a book and toy store located at 27 Central St.