Ok. I have the same problem. I didn't notice that before. I always check audio sync in preview so I always go to properties.
UPDATE: Ok I finally found the problem. It will be fixed in new version. New version will be released after NAL-HRD patch is 100% stable.
http://forum.doom9.org/showthread.php?t=152127
Temporary solution :
Usex264x64=0