Mine is exactly the same with regard to the steering. Its just because its not particularly aided by the power steering, so if you have a lot of lock on, the inertia of the wheels will keep it pointing in the direction you turned rather than coming back to centre. Mainly I find it only happens when I turn tight turns (ie junctions), round rounderbouts it will return to centre. Also after reading the others posts, it should if you are going in a near straight line, return to dead centre, and not require any input. If it does then the tracking will be out.
Refurbed Rays are very common. They bubble a lot and anyone anal (like most of us on here!) will have them done. Ask them why they were done and if they say bubbling or corrosion, you know it was legit