Why do the engines of the PAK FA (Sukhoi T-50) seem not to be not aligned parallel to each other? The nozzles of the Sukhoi T-50 seem to be aligned not perfectly parallel. However, it is not very pronounced.

What may be the reasons for aligning the nozzles engines not perfectly parallel.

Edit: in my original post I asked about the nozzles, however, as it was pointed out, this plane used 3D thrust vectoring, so the nozzle arrangement might be this way by chance. However, also the engines seem to be aligned not perfectly parallel. The question has been edited accordingly.


Image source Wikimedia

Edit 2: Here is another picture 
Image source, Wikipedia again
The Sukhoi T-50 operates Thrust vectoring nozzle control at low speeds. The nozzles are a part of the Fly By Wire system and will deflect as per the control input given by the pilot. The nozzles move in coordination with other flight controls and it is not necessary for them to be parallel in all conditions of flight. However on the ground they will appear to be parallel.