A popular St. Lucie Denny’s got cited with a warning after inspectors found food being held at unsafe temperatures — a concern that can put diners at real risk. The Aug. 31 routine inspection, conducted by the Florida Department of Business and Professional Regulation at the eatery at 10111 S. U.S. Highway 1 in Port St. Lucie recorded six violations and ended with a warning issued and a follow-up inspection required.…