As much as I want to believe this is true there is no visual or physical evidence of any kind. Also, no one else has come forward to confirm this. That is a problem IMO.
He probably didn't think anything of it at the time, and had no inkling until the next day. It's too bad though, that he didn't take any pictures of whatever he was transporting, or the paper order he was given, regarding where he was to go with the stuff. There has to be a log book or some device they have to enter info into that tracks their hours, and details of their travel. I remember one time, 4 or 5 years ago, when my regular mail carrier was being dogged by a supervisor, who was walking behind him tracking him with a device to see how long he spent delivering the mail on his regular route.