I am guessing that is how they did it, they just put the date the submitter had on the submission form on the label but they couldn't be sure it was that date when they had it in hand so they determined it ungradable for that reason. To be honest it doesn't look like the date is 1798 to me, it looks like it is 1800 or 180* to me. Of course this is just going by the picture and not sure what it looks like in hand