I'm sure it's to set up the next rhyme "Frigh-ten -ing".
Bad lyric writing (unless your E.Y. Harburg -- who often did that sort of thing INTENTIONALLY to have "fun" with the rhyme scheme)
So, if Harburg did it intentionally, how are you so sure that Smalls didn't? What automatically makes it bad lyric writing for Smalls but not for Harburg?
