Alright, I've replayed that first encounter twice now from a fresh "save".
One time I managed to get the monster camping me (maybe it was just stuck on its legs and was actually slowly leaving? I waited for a minute at least).
The other time it didn't camp. I actually played all the way through this time and man you got a cool game.
Back on the topic of killing me in the locker. Both times the monster didn't touch me in the locker. there are multiple signs of whether the flashlight is on or off (sprite changes, audio, lights), but the actual light is fairly dim so I think it's likely I simply had the flashlight on while inside.