Hey,
first of all, I think thats a really nice idea for the contest and one can tell you already put a lot of work into this.
If I may give some constructive feedback, I'd say that it isn't too short, quite the opposite in fact. I think it actually might be even better if you shortened it a bit (I know, if one works directly on something like that it always appears to be shorter than it really is, because you have already seen it over and over and know it by heart
) and then tried to make the shortened scenes a bit more interesting and diverse.
For example it feels like there's a bit too much walking right now where not much happens. Maybe you could spice that up with some extra frames of animation, like the character looking nervously over his shoulder or the light of the lantern flickering. (I really like that little moment at 3:18 where he looks to the side, its timed pretty well.)
I think you could also improve the illusion of him moving forward - for example have some pillars or similar pieces of environment move past him in the darkness or have the lantern light the floor under his feet, which scrolls in the opposite direction of him.
I also think it could be very atmospheric, if his lantern would flicker and become dimmer at the end when the grunt approaches... or if the camera would zoom out more, heightening the sense of that dude being really small and alone. o.O
Keep up the good work