when /.autorelabel is set, fixfiles runs. But, it has special checks for specific filesystem types, and ext4(dev) is not among them. So, fixfiles doesn't do anything for ext4, or other non-listed but selinux-xattr-capable filesystems.
Fixed in policycoreutils-2.0.36-1.fc9
Changing version to '9' as part of upcoming Fedora 9 GA. More information and reason for this action is here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping