Apple SU requires 2x reboot on install

I'm tracking down why my InstaDMG build train is producing un-bootable images. It turns out that one of the apple SU's im using currently testing requires 2 reboots of the system when installing it normally. In the past I have seen a server SU require 2 reboots but this one is for the client OS. Can InstaDMG handle a .pkg that requires this? If apple releases a SU that does this it seems like instaDMG would be crowbared. I'm working back through my .pkg's to make sure that the problem is this specific SU. Blake