I'm testing a used 24-105mm L IS Canon lens. When I put my Canon 60D in Movie mode, and the lens in Stabilizer On, the motor makes a continuous sound. It's the same sound that is made when the camera is in still-image mode and you depress the shutter halfway. But when the camera is in still-image mode, the IS motor is only on briefly, while the shutter is being pressed. In Movie mode, the grinding sound is continuous (which makes sense, but still - it makes me wonder whether there is "wear and tear" happening).
My question is: should the IS on this lens be this audible? Does continual IS action create a maintenance issue with these lenses? The "kit lens" that came with the camera (18-135mm) is not nearly so noisy in comparison.