COPPERDOG

I have a Benelli Nova 12ga 28" barrel that I patterned today with an Indian Creek Black Diamond Strike .665 and Hevi-13 3" 2 oz #6. At both 40 and 50 yards I put the red bead where I wanted to hit and the center of the pattern was about 8"-10" high. Is this common for a pattern to be high but centered? I would think the pattern should be centered where I sight down the rib and put the bead. Has anyone else had this problem with an Indian Creek? Copperdog