As a retired Employee of the USPS I can assure you the carrier is at fault. At no time should a package (i.e.piece of mail) be left unsecured. If arrangements haven't been previously made to leave packages in certain areas then said package suould be returned to the post office with a reciept left at the address.
Flat black, let dry thoroughly, rub with tissue. Leaving just a hint of flat in the cracks and cravaces indicating a duller sheen where there would be less ware.
I think many of you are right. We (baaa) should except the manufactuers claims on MPG (baaa) and all the other ###### they shove down our throats (baaa).