According to the Facebook Developer Blog,
offline_access Permission Removal
offline_accesspermission is deprecated and will be removed July 5, 2012. Until then, you can turn this change on or off using the “Remove offline_access permission” migration. On May 2, 2012, we will automatically turn the migration to “enabled” for all apps. If this breaks your app, you can turn the migration back to “disabled” until July 5, 2012 when it will be permanently “enabled” for all apps. Please see the Removal of offline_access Permission doc for more details.
Hopefully, this would give you (or Facebook) more time to debug and fix the related problems when offline_acess permission is removed.