Zuiko 9-18 decentered ?

Hi I have just got an used Zuiko 9-18 lens. I have it mounted on my Oly E-PL2   with Mmf2 convertor.
The picture's left side is quite soft compared to the right side or to the      center.                                                                         
It's visible for all apertures but 4 and 5.6 apertures are worse.
If I move my focus point area to a left side of my display screen during a focusing and make the same shot then left side becomes sharp but center is not  tick sharp any more and right side is soft. So there is no combination how to have center, right and left side of the picture sharp at once.
Does this sample suffer from decentering problem or a field curvature or both ?
Do you experience same troubles with your 9-18 ultrawide ?

Shold I rather send this lens back ?
Thank you

Below are 100% cropped (left edge to center) pictures first one focused to the center second one focused to the left edge. As you can see the first one's left side is much softer.