That's what it's looking like, or at least something fungal. The Daconil I put on the plant yesterday seems to have stopped the spread. The last leaf stalk just looks lonely and pathetic, not lonely, pathetic and speckled today. Will be picking up another Gold Medal plant today, just in case. Thanks for that link, btw! That's insanely useful.

This is my first run with growing heirlooms. The person that sold me the Brandywine raved about the Sungold and sent me home with a plant for free. So far it's the happiest of the four 'maters, so I have no complaints about it whatsoever. :D