Did Heinlein invent TANSTAAFL?

The paperback edition of The Moon Is a Harsh Mistress I read as a teenager. 

The acronym TANSTAAFL — "There ain't no such thing as a free lunch" — features in Robert Heinlein's classic libertarian science fiction novel, The Moon Is a Harsh Mistress, which won both the Hugo Award and the Prometheus Hall of Fame Award.

Robert Anton Wilson referenced the phrase in his Schrödinger's Cat trilogy. Wikipedia explains,

" 'Tanstagi', an acronym standing for 'There Ain't No Such Thing As Government Interference', is the motto of the Invisible Hand Society, an originally fictional organization invented in the Schrödinger's Cat Trilogy. The acronym was deliberately intended as a reference to Robert A. Heinlein's TANSTAAFL principle.

"The Tanstagi principle is meant to imply that the invisible hand of the free market applies to government as well. In other words, contrary to traditional ideas of laissez-faire capitalism, government interference in the free market is impossible, since governments are inextricably a part of the market as a whole. 'Government' is not a separate institution—it is a word used to describe the actions of a large number of individuals subject to the same (at least qualitatively) pressures as everyone else. Both of these ideas are part of what is known as 'economic Taoism.'

"While it was first introduced in a novel, people claiming to be members or know of chapters of the Invisible Hand Society have occasionally appeared in editorial pages and on the Internet." 

As many of you likely known, the phrase "invisible hand" was made famous by Adam Smith. 

But did Heinlein come up with the phrase behind the acronym TANSTAAFL? Apparently not, according to a blog post, "Who Said TANSTAAFL First?", published by David Boaz at Cato at Liberty, the blog of the Cato Institute.

Boaz credits Heinlein with popularizing the phrase — "I’d say that Heinlein’s book generated the buttons and bumper stickers produced by the early libertarian activists" — but says research shows Heinlein did not originate it. 

Noting that the phrase also has been attributed to Milton Friedman, Boaz notes that the Quote Investigator has traced the phrase "There ain't no such thing as a free lunch" back to a 1938 newspaper article titled “Economics in Eight Words.”   Evidence suggests the unsigned piece was written by Walter Morrow, editor‐​in‐​chief of The Southwestern Group of Scripps‐​Howard Newspapers, Boaz says.

"Heinlein just might have read one of the 1938 newspapers in which the 'Eight Words' article appeared," Boaz suggests.