It's warped. The warp may be reduced by removing the hood, set it on a flat surface and putting pressure on the rear center. Measure the side to side dimension at the rear on the car and off to confirm it is warped. There is another possibility, the sides where the hinges are located have pushed the center up, aka warped it on the car. This happened to a friend's 67 hood when the car got hit on the LH side. The statement of no "known" body damage may be questionable.
Jim