Bullet hole glitch

In Halo: Combat Evolved, there is an odd glitch that is very easy to see/perform. Basically, shoot a BULLET (not a rocket, needle or plasma bolt) nearly parallel to any surface that will leave a bullet hole (i.e. a wall, hard ground, not dirt or ice). At the point where the bullet hits, there will be a mysterious splotch of human blood. One theory is that the blood is the player's blood, but this couldn't be right because the bullet bounces to the player but his blood is in the bullet hole.