Not sure if this has anything to do with it, but since 11th March 2010 the airspace between Frankfurt and Amsterdam has been reorganised under a project called AMRUFRA ( AMsterdam, RUhr, FRAnkfurt) with the aim being to streamline traffic flows between sectors.
I canīt find much about it on the web, maybe the DFS or LVNL websiites will have some information.