You say "totally black already". I assume that it was not very dark when you picked the bike up after the service. If it was still black at the shop, then yes, maybe they did not even bother to change it.
Then again, my oil turns black pretty quickly. From what I understand that is a "feature" of new detergent oils. They do such a good job suspending the dirt that they turn dark quickly. That should mean nothing with respect to how the oil performs, however.
When it comes to havoc, no one wreaks like me! - Dr. Heinz Doofenshmirtz
I will never be good and that's not bad. - Ban-Anon