Boxxer World Cup leaking oil

I've recently bought a 2nd hand 2008 Boxxer World Cup fork, and I notice there is a bit of oil being left on the stanchions. Apparently they had been re built not long before I bought them, so it seems weird that this is happening. Do the Boxxer World Cups have a reputations for this? Is it a major to fix, or is it just the case of replacing the seals which most bike shops should be able to do?