I always thought that "Gilded Age" was a simple play on the words, "Golden
Era", the kind of irreverence that employees often show to their
employeer's name.  Twain, or any of his coworkers at "The Golden Era",
could have come up with it; Twain, who distanced himself from his Western
roots, may have been reluctant to discuss the genesis of the phrase.

Anyhow, that's my (unsubstantiated) two-cents' worth.

larry marshburne