Thank you cobba, I'll try that this evening.
If it's the wheel, then i've been riding it as it is for one whole year (not a lot though, about 5 - 600 km), so unless the previous fork had such an offset (which I doubt) what is the danger of running with it as it is? I'd still ask the question if the fork was at fault, what would be the problem with running with it as it is?

--- LE:
saddlesores: just saw your edit now; I'll find out today if the dishing is at fault as for the wheel, the fork has normal dropouts (unlike my previous fork it has no lawyer lips - I was very surprised when it took some effort to push the wheel all the way up the droputs and the engage the qr) and I'm pretty sure the axle is pinned at the same level in both dropouts.

--- Even later edit:
saddlesores: only now did I realize you where asking about the original fork; as far as I remember, yes it was centered (I never really cared actually, it's only on this new fork with it's huge distance between crown and wheel that I bothered to check).