If you have an uphill/downhill rail between blocks on two different vertical levels, and you destroy the upper block (that the upper end is attached to), both the rail and the block you were mining drop (assuming you can obtain the block you were mining with the tool/item you used). I find this odd as the rail is still resting on the bottom block which was not destroyed, and I believe it should go back to a flat configuration as opposed to dropping as an item.