I have a relatively new 11/08 Canon D40 with a Canon 28-135mm f3? I purchased them as a kit. When the lens is at it's retracted? position the end of it can be moved back and forth about 1/8 of an inch. It seems to have excessive play in it. When I have it zoomed, the play at the end of the lens is minimal. Also when I hold the camera with the lens pointing down, the lens falls or zooms on its own. Is this normal for this type of lens?