I use the automatic lens cap and I also have a filter adapter attached for the occasions when I want to use a polarizer. The filter adapter has a nice smooth taper so the blades on the automatic lens cap can glide right over it when the lens is extended beyond the blades of the lens cap. When closing the lens, it does do a double bounce as you described. In taking a closer look at the positioning of the lens as I zoom from min to max zoom, I noticed that the lens actually recesses in slightly as I proceed to zoom out. Then it starts to extend again and reaches its furthest position at max room. So the double bounce may be a result of the lens proceeding to stick out again as it reaches the minimum zoom position before it completely retracts for shut down.