found out what that was....
it's the shipped NANNY Perl script. it makes sure the named stays running.
one of the tests it runs to check if the name-server is responding is:
dig +short . @localhost > /dev/null
this was the reason for the odd logentries.
OK, then is there a way of logging everything except "...client 127.0.0.1#3015: query: . IN A.." like regexp?