Disk devices changed after upgrade to current

I have just upgraded my system from 7.2 to 8.0 using a source based
upgrade. After rebooting it for the first time the server unfortunately
failed to come back up. I had a look at the console and found that it was
failing to find the root device and prompting me for it. By manually
entering it I managed to boot the server and could then see the problem.

In the 7.2 fstab my root partition and swap space were ad4s1a and ad4s1b
but after booting the 8.0 kernel these seem to have changed to ad4a and
ad4b so I set the new names in the fstab and it's now working fine. I read
through the UPDATING file before I did this but I couldn't see any warnings
that this may occur. The only entry that's possibly relevant is 20090320
talking about GEOM_PART.

My question is is this change expected behavior or has my system done
something strange? If it's expected then I think a warning could be needed
for when more people decide to do this upgrade after 8 is released.

Also I'm seeing a lot of messages logged to syslog saying "kernel: NMI ISA
3c, EISA 0" and "kernel: kernel trap 19 with interrupts disabled" over and
over again. I commented out most of the usual debugging stuff from the
kernel file whilst I was making my own kernel but these messages are
obviously coming from somewhere else. Can somebody point me to what I need
to change to disable these apparent debugging messages?

Other than that everything is working well so far. Good work!

Regards, Matt.