Maybe clean and polish the barrel?
Moving your eye position can change the apparent position of the reticle with non parallax adjustable scopes. If yours is not an adjustable objective scope (you can focus it for different distances), you could be having this problem. Most Non AO scopes have a specific range at which they have no parallax, and it's usually more than ten yards. You can tell if you have parallax if moving your eye position causes the reticle to move relative to the target.You can always use this problem as justification to buy a really nice scope.
From a picture, it look like your POI is shifting up-left.How you release a trigger after shot? If it is too soon (quick), this might happen.I had a similar problem, I was not even aware of it. I noticed it after I store camera while recording was still on (forgot to swich it off), so it continue to record me.Old habbit from army, when I was shooting automatic weapons in short brusts. Trigger have to be released quickly to shoot about 3 bullets only in automatic mode.After I worked little bit on, not to release the trigger quickly, POI shifting up-left stop.