The problem you described seems very minor to me.......it' s a couple inches at 200 yards?.....and the groups are still good but off center?......this seems like simply relieving of stress in the barreled action to me.....it' s a normal and natural thing that goes on for up to five years.....it doesn' t happen over night.....it' s a change that happens over several months.....relax.....it' ll be ok!!

Damn few riflemen can detect that stress relieving.....congrats.....you' re one in a thousand.