..it's the X-Files theme.

{{the following is a blatant internet ripoff of X-Files}}
later that same day
Skinner laid there beside Mulder and let himself be petted and soothed. "The idiots," he grumbled.

"Shh," Mulder said for the fifth time. "Nothing happened to them. It's all right." So they were lying there in silence, perfectly able to hear a long, rich moan, then a flurry of coughing and some hastily smothered chuckles from the next room.

"Hell!" Skinner whispered furiously. "'Nothing' happened to them, huh?"

"What was the strange thing the dog did in the night?" Mulder quoted ruefully. It took him another half hour before he was able to calm Skinner enough to sleep.

In the morning, they said nothing about it.

A Dog in the Manger, by JiM

---

here's what "Mulder" was alluding to, from Glory Road:

"...If it hadn't been for the strange thing the dog did in the night, the busies would have nabbed us?"
"What was the strange thing the dog did in the night?"

---

could Mark Haddon's novel The Curious Incident of the Dog in Night-Time been inspired by Heinlein's line?
the story doesn't (seemingly) relate in any way at all; but I'd sure like to like to ask Haddon about that title.

[my sincere apologies to Mulder/Skinner fans; that ripoff is truly dreadful.]