Looking for a little anecdote about reading before bed.

Last night I was chatting on the interwebs, and someone mentioned that their old roommate had watched Pulp Fiction, Goodfellas, or Scarface every night to go to sleep. This reminded me of an old anecdote that went more or less like this: An author meets one of his lady fans, who gushes that she loves his books and reads them every night when going to bed, and they help her go to sleep. The author, straight-faced, says that no writer could hope for a greater compliment.

It goes more or less like that, because no amount of googling last night could find it for me. I think it was Mark Twain, but I’m not sure; Mark Twain is one of those guys who, like Einstein and Jefferson, naturally draws false attributions. Is there anyone here who can help me? It’s driving me mildly crazy.

Might be from “Stranger in a Strange Land” by R.A. Heinlein.

Dawn Ardent to Jubal Harshaw. While the latter is visiting a Fosterite Church.

…this is the famous Doctor Jubal Harshaw here by me-"
“Really? Doctor, I think your stories are simply divine.”
“Thank you.”
“Oh, I really do. I put one of your tapes on my player and let it lull me to sleep almost every night.”
“Higher praise a writer cannot expect,” Jubal said with a straight face.

Heinlein may have lifted the quote from someone else though.