Weighted pressure plate on powered hopper bounces items

I put a weighted pressure plate atop a powered hopper, and tossed items onto the WPP.

As I expected, the items were not absorbed by the hopper, and the plate provided a proper signal on its own level.

What I did not expect was that the pressing and release of the pressure plate would bounce the item into the air, this repeating until the item bounces off the plate. But that's what I got, with some bounces long enough to darken a redstone lamp hooked to the plate signal.