That missing sentence for IMC will probably be added to the next list of errata.
I just looked at the text in the 2002 NECH CD Rom and in the PDF 2002 version, and the language is in both places.
I also looked at my NFC CD from the May meeting, and they are there too! I guess the errors are found in the 1st printing.
If you are a member of NFPA you can access the NEC online, I wonder if that version is with the corrections.
Listen, it is not easy and before computers and the internet, we did it all by the "good old evil eye" and it was time consuming, but still was not easy to find all of the errors in the 1st printing --- there will be errors that show up through most of the printings and that's why no one is perfect.
PS: Look at the * notes in Table 310.13, are they in the correct places?
Joe Tedesco, NEC Consultant