Interesting. I used to get similar from other games in the early 3d era - first noticed it watching my brother playing Dark Forces, and we both felt it from that. Never did get it from Marathon though, and played it rather a lot.
I always thought it had something to do with the incredibly natural feeling of movement in the game - the bouncing that made you really feel like walking/running, that every other game then lacked, and felt instead like sliding along, most unnatural. Something anyway, Bungie performed magic, and the Marathon games are still the best FPS ever.