Originally Posted by
striknein
Then take it to a LBS and see if it can be fixed by cold-setting.
It can't, you can only cold set a complete rear triangle side to side and if it were off center, the wheel would have the same gap on the ss and cs. It could be that one cs is higher than the other or a ss is bowed, or....there's no way to tell what's causing the misalignment without some good measurements.
like Carleton said, this isn't rare for budget frames, but on the bright side it won't cause any problems with the ride, durability of the frame, etc.