No, it's not a new change at all. You're simply lucky that you didn't run into it, and apparently you aren't a regular reader of the Rewards Network forum and so you didn't read about the countless references to it before there.
Here's one thread from that froum (from 2010) discussing multiple ecounters with this very problem:
http://www.flyertalk.com/forum/idine...ring-amex.html
(If you want to continue discussion on this particular issue, please do it in that linked thread. Thanks.)