My guess is that there is something wrong with freebsd-update. There is
another thread here one the mailing list. And here is another thread at
BSDForen.de I have started:
http://www.bsdforen.de/showthread.php?p=251220#post251220
I am experiencing the same issue. I am no BSD-expert, but what I found
strange is that if you compile your own GENERIC kernel+modules the
freebsd-update tool tries to update the nfsd.ko module which would
indeed result in a different checksum for nfsd.ko + a different
linker.hints.