snapshot - 5.4 panic

[Per olof Ljungmark]

I did a test install of snapshot(8)
http://people.freebsd.org/~rse/snapshot/
It seemingly worked well, I could mount the snapshots as expected etc. 
This morning when I rebuilt the system from 5.4p1 to p4 and rebooted.

At boot the system panicked:
panic: snapblkfree: Inconsistent block type

setting
amd_enable="NO"
did not help

I did a "rm -rf .snap" on all concerned slices and that stopped the 
system from panicking.

I'm not particulary fluent with what snapshot does and would like to 
hear from anyone that might have a clue.

Thanks,