I don't know either, but I think you're right; it's supposed to be the Fugue in G Minor, which not only fits better but is also much more familiar.

When one considers how that book was edited (constant back-and-forths between Garrison Keillor and the Pankakes), errors could easily happen.

It's also perhaps worth noting that Keillor's radio career began as a rebellious DJ on a classical radio station. :-)