Guys, I think my hood is flying!

Gentlemen: This is a new one for me. When I'm at 70 mph in my 74 Duster, the left front corner of my hood lifts up by about 1 inch and shakes slightly. The right front corner of the hood is in its fully down position and rock steady (no shaking). Ideally, both front corners should stay down and not shake. As I decelerate through 45 mph, the hood goes back down and stops shaking. When stopped, the hood looks perfectly adjusted and doesn't stick up anywhere. Is it possible that the hood is creating "lift" like an airplane wing and pulling up as I go faster? When the hood is closed, it appears to be resting on top of the rubber vertically adjustable bumper. Any ideas for fixing this problem? Thanks.