Ben Selvin and His Orchestra's "Oh Gee! Oh Joy!"

For the last week or so, I've been making my way through a 10-CD set of George Gershwin works.  To-day, it's disc 7, subtitled "The Later Broadway Musicals."  I'm actually not sure if I'd noticed this before or not, but I recognized a melodic phrase in "Oh Gee! Oh Joy!" (performed by Ben Selvin and His Orchestra) that's also in Gershwin's Rhapsody in Blue.  After the initial "Oh gee! Oh gosh! Oh joy! Oh golly!," there's "Oh gee I'm happy 'cause my baby loves me."  The melody to which it's sung is something like this:

The same phrase (a half step higher) is in the Rhapsody in Blue.  In the recording I have by the Royal Philharmonic Orchestra, it's in the piano part at about 6:52.

I lookt up "Oh Gee! Oh Joy!" in the index of Edward Jablonski's Gershwin: A Biography (which I actually haven't read yet) and found that it was written for Rosalie in late 1927.  The Rhapsody in Blue is from 1924, so it seems like Gershwin re-used that melody from the Rhapsody as an introductory phrase in "Oh Gee! Oh Joy!"  Of course, there's also the possibility that this feature is unique to Selvin's version, but in either case, that melody came from the Rhapsody first.