WARNING: Expected rawoffset 0, found 63?

[Peter Steele]

>Are you gmirror'ing the BSD slice? 
> 
>Wrong: 
> /dev/ad0s1 
> /dev/ad2s1 
> 
>Right: 
> /dev/ad0 
> /dev/ad2 
> 
>That's what it sounds like to me. 

I don't think that's the issue. I read many articles on how to mirror slices, including the BSD slice, and in earlier tests I never saw this error. Something in my latest incarnation appears to be wrong though. This is one of the links I've modeled my work after: 

http://people.freebsd.org/~rse/mirror/