CREATE TABLE table_14351 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Game site" TEXT, "Record" TEXT, "Attendance" FLOAT)

Name the date for w 31-28
SELECT "Date" FROM table_14351 WHERE "Result" = 'w 31-28'
SELECT "Date" FROM "table_14351" WHERE "Result" = 'w 31-28'