[CentOS] Error installing latest CentOS kernel from %post section of kickstart

I'm running the command "yum -y update" from a script called from the the post section of my kickstart config file, and I get the following error:

    Installing     : kernel-2.6.32-71.29.1.el6.i686                       185/378
grubby fatal error: unable to find a suitable template

After the install, if I log in to the system and remove that RPM and then re-install it with "yum install kernel", the grub.conf file is updated correctly.  Any ideas why this might be failing from kickstart?  Anyone else seen this?

Alfred