Parallax becomes an increasingly large problem as magnification increases and 9x is about the point where it starts to be an issue.
Properly mounting the scope so that your eye is naturally centered on the axis of the cone of light produced by the scope will reduce the error.
A contributing factor is the distance the scope is set at to be parallax free. Most center fire scopes are set up to be parallax free at either 100 or 150 yards, while most rimfire scopes are set up to be parallax free at 50 yards. I believe Vortex uses 100 yards on that scope, so it's not bad for a .22 LR that will do dual short and long range duty.
If you are doing long range shooting with a precision .22 LR, the 100 or 150 yard parallax works well. For short range shots, just dial the magnification back to 3 to 4x and the parallax error will be minimal.