[CentOS] rpc.idmamd warnings/errors

Hello,

Every 15 minutes I get an error on NFSv4 server:
rpc.idmapd[1889]: nss_getpwnam: name '0' does not map into domain
'aaa.test.home'

I have fully updated Centos 6.4 machine. All shares seems to be ok.

Does anybody know, what does this error mean?

Thank You.

-- 
mv