That is off a bit more than I'd expect.
Did you level the crosshairs prior to beginning sighting in?
Just like with a rifle, it's important to make sure you've got the crosshairs leveled for best accuracy.
Just place a level across the rail & also a small one on the top turret cap. If both read level you're good, if not adjust the scope a bit in the rings to get it right on, easy to do.