[CentOS] NFS static ports configuration

A couple of RHEL5 books I'm reading at the moment suggest port numbers 
above 1024 for statd, lockd, mountd and rquotad (eg 38001-38006 or 
32764-32767) when configuring NFS to work with a firewall.

The default /etc/sysconfig/nfs on CentOS5 however has defaults under 
1024, such as

mountd	892
statd	662
rquotad	875

Is there something security-related going on here that I'm not aware of, 
or some other explanation? Neither text mentions the use of ports under 
1024 at all.

Thanks
Mick