CREATE TABLE table_41243 ("Date" TEXT, "Tournament" TEXT, "Winning score" TEXT, "Margin of victory" TEXT, "Runner ( s ) -up" TEXT)

Which date was the Memorial Tournament held on, when Payne Stewart was runner-up?
SELECT "Date" FROM table_41243 WHERE "Tournament" = 'memorial tournament' AND "Runner(s)-up" = 'payne stewart'
SELECT "Date" FROM "table_41243" WHERE "Runner(s)-up" = 'payne stewart' AND "Tournament" = 'memorial tournament'