It's an interesting behaviour - like leaning into corners when playing a driving game, or peering into the monitor at funny angles, because you think you can 'see' around corners etc. We are hard-wired to respond in certain ways, and even when playing a game we just subconsciously react.
Says something for the immersion of a game, too. I've seen Rift users literally trembling and close to tears, having experienced a simulated rollercoaster ride! I always winced slightly when entering a station, sans docking computer, in the original Elite. The sound of all of my shields being shredded still gives me nightmares.