I have the answer to your problem. I had this very same problem. There are some little rubber shoes thingies on the inside of the hatch that rest on the flip top deck. Those are what make the squeaking noise as you drive and you move around. To stop it I used a heavy hair brush and worked it over the spots being rubbed. The idea is to keep the spots on the deck being rubbed as "plush" as possible. I hardly ever hear it anymore.