I also read something recently on viscous fan clutches and that they are always "engaged" and spinning. I had replaced mine as someone had just glued it solid to the bearing when I originally bought the car and I noticed it never loosened. When the clutch warms up and at higher speeds, they are suppose to "loosen" and still spin pretty fast but not at the same high rpm as it did when it was cold. After I drive my car and get it warm, if I open the hood and sping the fan, it does not spin freely but it is definitely easier to spin vs. being cold (goes about 1/4 to 1/2 turn with a quick flick of the wrist). I bet your clutch is OK.