Yum unable to install while yum-updatesd running

Back in the old days, when periodic yum updates where a cron-job,
I was able to issue 'yum install ...' or 'yum update ...' commands
with impunity.

I'm running CentOS 5.1 and seeing the following:
[root@dmurray ~]# yum install perl-Date-Manip
Loading "installonlyn" plugin
Existing lock /var/run/yum.pid: another copy is running. Aborting.
[root@dmurray ~]# echo $( cat /var/run/yum.pid )
16744
[root@dmurray ~]# service yum-updatesd status
yum-updatesd (pid 16744) is running...
[root@dmurray ~]# rpm -q yum yum-updatesd
yum-3.0.5-1.el5.centos.5
yum-updatesd-3.0.5-1.el5.centos.5
[root@dmurray ~]#

If I merely _restart_ yum-updatesd, I can then immediately
do a 'yum ...' command as desired.

What's the idiomatic way to update or install via yum, while
yum-updatesd is running?

Thanks!