Here's the Boeing Service Bulletin number: 747-78A2181
Google found this:
http://www.skybrary.aero/bookshelf/books/1319.pdf
"This service bulletin will prevent the Group A leading (LE) flaps from automatically retracting if the flap control unit (FCU) receives dual REV Amber messages from the thrust reversers".
Unstow signals from symmetrical engines (two inboard or two outboard) previously triggered Group A (midspan and inboard) LE flap retraction.