Not that this is your only problem but I have seen the same thing over and over from people sighting in. You should always adjust your left to right adjustment when you are still fresh and at the maximum yardage you can shoot (40yds or so) and as PABowhunter wrote in the earlier post then go back and shoot at 20 yds and you will find it to be adjusted properly. I believe if this does not cure the problem you may be canting the bow and should put a level on your sight to correct this problem. I dont know how serious you take this but you should visit the Spott Hog sight which has articles on the different axis adjustments especially important when shooting at longer range from a treestand or down hill.
Good luck
BD