recently i just bought 2nd hand nkkor lens 55-200 vr from cs member. it's my first vr. i use nikon d-40. i just discover if i press halfway the shutter release button n let the lens focus, n than release it again, the lens view will move dwn a little bit. wit some kind of click. about 1 cm of what i saw in the viewfinder. but if i turn off the vr, it will gone. it will stay constant where i want it to be. is it just my lens, or every vr do it? pls give some light. thanks