"Matchbooks are always clues, right?"
Dr. Seth Hazlitt
'MURDER, SHE WROTE'
"THE DREAM TEAM"
Seth's question to Sheriff Metzger shows that the good doctor may have been an avid mystery lover, perhaps even Jessica's most dedicated reader.
Two examples from other media in which a matchbook clue played a part (and which wouldn't create any Zonks for Toobworld!) would be:
"Halfway House" by Ellery Queen
Yes, Ellery is a TV character, several times over in fact. But he was also a mystery writer and so Dr. Hazlitt might easily have found that novel in the Cabot Cove library.
This Harrison Ford movie premiered in 1988 and this episode of 'Murder, She Wrote' was first broadcast in 1995. So there's plenty of time for Seth to have seen it... probably once it was on free TV, of course.
There's a "Thin Man" sequel in which a matchbook provided a clue for William Powell as Nick Charles. But Nick Charles was a TV character who wouldn't be prominent in Toobworld for another decade.....
Can't get more trivial than that!