Thank you for the clarification. The possibility existed, I believed, for an error of transcription, which is why I brought the matter forward in the previous post. Better to nip it in the bud than possibly let it go on and on in case there really was an error. As we have seen recently with the 1954 series $50 and $100 notes, mistakes can go undetected and uncorrected for a very long time, and the passage of time builds precedence, making it that much harder to get at the truth.
A range of 27,000 notes would be 3 consecutive reams of 9,000 notes. It was common in the past, when reams were much larger, for consecutive reams to be amalgamated into one serial number range. It is much less frequent to see these smaller reams in clusters, though there is nothing unusual or wrong about it.