American Airlines said its flights had resumed after a vendor technology issue briefly led the carrier to halt them Tuesday morning, on a high-pressure day for holiday travel. The Federal Aviation Administration shortly before 8 a.m. ET canceled a ground stop that had been issued earlier for all American flights at the carrier’s request. While some American flights got off to a late start Tuesday morning, the hourlong ground stop hadn’t resulted in mass cancellations, according to Cirium, an airline data provider.