[BIND 9.2.1] trailling garbage

Hi all,
I have an error on my DNS CACHE for some domains.
example, for domain www.back.euro.st, i have this following output in the named.log (level 2) :
Aug 17 10:57:23.827 debug 1: createfetch: www.back.euro.st A
Aug 17 10:57:23.834 debug 1: message has 4 byte(s) of trailing garbage

If anyone have an idea to fix it.
I haven't found solution via google or mailing-list archive (no answer from my previous request)

Thanks in advance.
Laurent.