David Fincher and flashlights

I've never seen this mentioned anywhere before, but David Fincher seems to be obsessed with flashlights. In Se7en there are some scenes of cops in dark rooms shining flashlights. In Panic Room, Kristen Stewart does Morse Code with a flashlight. Even in The Social Network there's a party scene towards the end where cops show up with flashlights. I'm pretty sure Zodiac had some flashlight scenes too- I can't remember. You can go back to David Fincher's early work- Aerosmith's video for "Janie's Got A Gun" has cops with flashlights searching a car.