Which direction was in front of him? My guess is, if you are right handed, the shot went left. Your arrows could be on the stiff side to begin with. Then when you shoot down, if you don't bend enough at the waist, your draw will shorten, further stiffening the shaft. Add a little bit of buck fever and the draw could shorten a bit more, adding to the stiffness. Depending on the distance of the shot, those factors could easily put the arrow a yard off target.
On the other hand if the arrow went right, I'd make this guess: you plucked the string a bit coupled with wet feathers and bingo, a yard off again.
Now I'll add one other possibility: didn't pick a spot.
In case you are wondering how I came up with these possible scenarios...well, let's just say I've seen it happen...first hand.
