What were you using to remove the old seal that scratched the camshaft? In any case, when you scratch something that rides against a rubber seal, do your best to buff out the scratch, or at least remove any sharp edges with fine sand paper (600 grit, as much as you like, 400 grit okay, but don't go crazy and remove too much metal, and finish with 600 grit after) and cross your fingers. Unless the "scratch" is a gouge, you'll probably not shave too much time off the life of the seal.