I'm watching the Steelers and SD just went ahead 20-17 and kicked-off with 2:56 on the clock. It's a touchback, but the clock is running and the Steelers snap the ball at the 20 with 2:38 on the clock. Shouldn't the clock still be at 2:56? Clock should never start on a touchback, let alone keep running. But the coaches didn't complain or the announcers notice. Any any reason for this?