The ABYK is just an update of the origional AUAH software that GM used to address some issues that 90 owners were complaining about. There was no recall issued, just a TSB on the symptoms customer's were/could complain about.
In the event of a customer complaint about hot idle fluctuation and or hot surging the TSB says to use ABYK as a service replacement to address the customer's complaints. If you would like to see the TSB is over at the netregistry site, in the "TSB & Recall" section.
Tom