I see LOTS of flat-packs do this.
The best transistor story I ever heard was from Sam's predecessor Jack
Darr. There was an uncontrollable hum in a TV's sound that developed
when the case was removed. The sound altered volume when the
technician's hand was moved nearby. Turns out that an audio
transistor's black epoxy case wasn't black, but translucent brown; the
carbon black hadn't been mixed properly at the factory. The
transistor junction is light-sensitive, and the 120Hz flicker from the
shop's lamps was reaching it through the translucent epoxy case.
M Kinsler