Yes.. it was a bad night
The probability of finding this particular glass element is pretty slim, but I will certainly ask Canon about it, just in case..
Anyway, I think the affected surface is definitely worth re-polishing, considering the condition of the rest of the glass.
Even without SSC coating, there will be a very small amount of visible inside reflections (because the icoming light beam will be reflected back and diverged on the convex surface of the element).