Yesterday's return from the alps was the first time I've driven my 4/4 sport at sustained high speed (140/150 kph for 6 hours with slower interludes when it was hosing it down) with the hood up. At about half distance when we stopped for petrol at Macon it was fine, but by the time we got home the central part above our heads was as saggy as an old pair of Y fronts. I left the hood up overnight, but still the same today. Is this normal ? Will it go back ? recalling my structures lectures at Uni I suspect that it has stretched outside the Hook's law region. What can I do about it ?