CREATE TABLE table_24250 ("No. in series" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

What was the original air date of the episode that had 4.08 million U.S. viewers?
SELECT "Original air date" FROM table_24250 WHERE "U.S. viewers (millions)" = '4.08'
SELECT "Original air date" FROM "table_24250" WHERE "U.S. viewers (millions)" = '4.08'