WHat it looks like to me is something I would expect. Take a look at the left image. The shadow is still there although less defined. It looks like the 'edge' actually bends up and that shadowed area is actually part of the underside. This is supported by the right image which shows the bend of the edge and the deeper shadow on the underside. I suggest going back to your modeller and viewing this in polygon mode very closely. You may find a not so straight edge here.