"Surfin' U.S.A."

I listened to the two-albums-on-one-CD reissue of Surfin' Safari and Surfin' U.S.A. recently, and while thinking about "Surfin' U.S.A." later, I noticed a small feature:  the line "We're waxin' down our surfboards" is sung to a descending phrase (Db Db Db Db C Bb F), musically giving a sense of that "down," although it may not be intended literally.