Hi Mavros,
I don't have a specific answer, but logic would suggest a manufacturing defect. I can see no aerodynamic benefit to asymmetrical stab incidence. How does it fly? Have you trimmed out the airplane satisfactorily? I would predict some pitch trim anomalies especially as speed varies and possibly some roll issues. That airplane has plug-in stabs, I believe, is the stab twisted (actually built crooked) or is there a problem with the stab tube holes?
Regards,
Will