I recently purchased a new D600 DSLR. The auto feature on tne screen indicates that everything is working properly to clear dust from the screen. However there is no vibration to be heard/seen. Is this normal? I also currently own an Olympus E-5 DSLR that has a very discernable vibration when I activate the same feature. My curiosity has the best of me right now as I'd like to know if I need to bring the camera in for repairs or consider all is well.