I agree with burnthesheep. If it looks fine, it probably is fine.

My 10+ year old Tarmac has numerous rubs, dings, and scuffs on the cf frame, some quite deep. It hasn't exploded yet.

But this post does highlight one of the issues with cf: damage can be invisible, though it is probably rare. You generally don't have that problem with steel, unless it is rusting inside the tubes.