[CentOS] rpc.idmapd error after upgrade to 5.1

Hello,

after upgrade from CentOS 5 to 5.1 I see the following error
in /var/log/messages:
'rpc.idmapd[2330]: main: open(/var/lib/nfs/rpc_pipefs/nfs): No such
file or directory'

The directory exists with the permissions
dr-xr-xr-x 2 root root    0 Dec  7 10:21 nfs

So is this an owner/permisson problem?
Should /var/lib/nfs/rpc_pipefs/nfs be owned by rpcuser?

# ls -al /var/lib/nfs/
total 24
drwxr-xr-x  5 root    root    4096 Dec  7 10:21 .
drwxr-xr-x 29 root    root    4096 Dec  3 07:25 ..
-rw-r--r--  1 root    root     701 Dec  7 10:21 etab
-rw-r--r--  1 root    root     685 Dec  3 07:24 rmtab
drwxr-xr-x  7 root    root       0 Dec  7 10:21 rpc_pipefs
drwx------  4 rpcuser rpcuser 4096 Nov 12 07:37 statd
-rw-------  1 root    root       0 Nov 12 07:37 state
drwxr-xr-x  3 root    root    4096 Dec  7 11:24 v4recovery
-rw-r--r--  1 root    root       0 Nov 12 07:37 xtab

My settings for /etc/sysconfig/nfs:

SECURE_NFS="no"
SECURE_NFS_MODS="noload"
RPCMTAB="noload"
RPCNFSDCOUNT=32
RPCNFSDPRIORITY=16
RPCMOUNTDOPTS="--nfs-version 4"
RPCNFSDARGS="--port 2049 --no-nfs-version 3 --no-nfs-version 2"
#RPCGSSDARGS="-vvv"
#RPCSVCGSSDARGS="-vvv"
MOUNTD_NFS_V2="no"
MOUNTD_NFS_V3="no"


regards
Olaf