I agree with what has already been said.
I tend to suspect a slight warp in a wing, very hard to see; well worth buying or making an incidence meter.
Grasping at straws here but I have another possibility.
Is the rudder connected by a pushrod to a horn on the left side?
When you pull 'g' a heavy sagging pushrod could be applying a little left rudder which would cause the problem you describe.
I nearly always use closed loop on rudder which avoids that problem.
Alasdair