^^^To expand on the quote Maurice posted above, per Heinlein's correspondence (1972-73, somewhere around there--I forget) with Harlan Ellison (quoted in Patterson's biography and on the Flat cat article on Wikipedia), he said (referring to David Gerrold ("nice kid") selling replica tribbles at conventions):
"If that matter had simply been dropped after that one episode was filmed, I would have chalked it up wryly to experience. But the 'nice kid' did not drop it; 'tribbles' (i.e. my 'flat cats') have been exploited endlessly… Well that’s one that did 'larn me.' Today if J. Christ phoned me on some matter of business, I would simply tell him: 'See my agent.'"
Now to be fair, obviously as a later date, we know that Robert and Ginny Heinlein became fast friends with Gerrold and left him some of their beloved cats when they grew too elderly to care for them. In turn, he dedicated a book or two to them, and so forth.
Sir Rhosis
"If that matter had simply been dropped after that one episode was filmed, I would have chalked it up wryly to experience. But the 'nice kid' did not drop it; 'tribbles' (i.e. my 'flat cats') have been exploited endlessly… Well that’s one that did 'larn me.' Today if J. Christ phoned me on some matter of business, I would simply tell him: 'See my agent.'"
Now to be fair, obviously as a later date, we know that Robert and Ginny Heinlein became fast friends with Gerrold and left him some of their beloved cats when they grew too elderly to care for them. In turn, he dedicated a book or two to them, and so forth.
Sir Rhosis