We no longer subscribe to the advance sheets so I don't have to deal with
this but it does look like a major change to me.
Since the US ISSN Center (also called NSDP - National Serials Data
Program) at LC assigned an ISSN (ISSN 0888-1774)to the former title, it
would create a new record with a new ISSN if it determines that there's a
title change. Otherwise, the bib record would just be updated. That is, if
you bring it to their attention.
Contact info. is on their web site at: http://lcweb.loc.gov/issn/
Hope this helps.
The Bureau of National Affairs, Inc.
Washington, D.C. 20037