1988 Cab whine/howl at higher speed

[desmo907]

I have a 1988 911 Cabrio with 24k miles. Today we took it for it's first longer drive. Each way was about 1.5 hours. On the way down the highway, several times, I heard what appeared to be a mid-range whine/howl that got a bit louder and higher over several seconds. I turned the wheels a bit but this made little difference but after a 5-10 seconds it went away. I was not sure if maybe it had something to do with the top (which was up). Maybe the wind hit something a certain way at higher speed (~75). This is my first Cab. After I stoppped I did see that the little clip above the windshield holding the molding around the windshield was off center so I slid it to cover the seam better. On the way home the noise didn't occur at all even at higher speeds.

My other concern was maybe a wheel bearing but the car as such low miles (brakes and tires are great).

Thoughts?