As ed mentioned, if the welds look factory and there is no splice further up in the panel its likely just poor workmanship at the plant. Since the bottom edge of the quarter panel has a lip that normally bends inward to try and shield water away from the seam - a worker would have had to taken some extra effort to make the panels go together. But have seen it before. Owners sometimes choose to correct the mistake during restoration.
Mentioning the finding before judging takes place (during their intro) is what I always suggest. Just a statement of findings , and having some pictures available should work - no name dropping is needed and often frowned upon
hi jeff thanks for inquiring my car was bucked on june 12 and built june 19/69- those two spots are filled holes ( body sealer) blob on lower inside too they're small dia holes . not my doing - could these holes in dropoff have anything to do with the calif vapor system in driver's side of trunk they're maybe 2 1/2 inches apart -................
IMHO no - for the retrofit there is no need to put holes in that panel. Return line goes into that panel up on the horizontal surface behind the wheelwell housing