Long before the U.S.Navy allowed us to drive one of their T-34Bs around, we spent a lot of time in pre-flight ground school.
Even now, over 50 years later, I still remember one of our instructors admonishing us: "OK, Cadets, you're flying along fat-dumb-n-happy. You know your aircraft 'cause you've been flying the exact same machine in your squadron for the last couple of months. "Suddenly, a needle-twitch causes your eyes to snap over to the oil temp gauge which shows about a 20 degree rise. Or maybe it's the oil pressure gauge that's developed a little 'jitter'. Whatcha gonna do? "Well, hell yes, you're going to reach up and thump the glass with a knuckle. It's gotta be the instrument, right, since the engine still sounds OK. [Soooo, WTF does high oil temp sound like, anyway?!] "C'mon, fellows, don't be an idiot! You've trusted all those dials for a couple of hundred hours and they've never been wrong before! The odds have proven that it's probably NOT that gauge! Damn it, believe your instruments!" Sounds like Joe had the same instructor!
