ah, i understand now! not sure why it's happening yet, but at least i can reproduce it. probably has something to do with the screen resizing and not scaling the camera view to account (or something).
i think the reason why it's all still playable is because the screen wrapping and enemy/pickup spawning are all dependent on the screen size (not a static value of what i expect the screen size to be). so when the screen size gets out of proportion, it messes up the UI and background image but is still playable. neat! thanks for the insight!