Lots of freebsd-update file changes on amd64 systems from 7.2-RELEASE-p1 to -p2

[Henno Schooljan]

I noticed that on my amd64 systems almost all of /bin, /sbin, /lib, / 
usr/bin, etc had changed from 7.2-RELEASE-p1 to 7.2-RELEASE-p2. On my  
i386 only some network drivers, libc and rescue files were updated.
Is this normal? Before installing the update I made a copy of the  
files, and it looks like only one or a few bytes of each file has been  
changed. For example the command

cmp -l /bin/dd /data/t/system/bin/dd

reveals that byte 1585 of /bin/dd changed from octal value 364 to 361.  
Lots of files have it this way. The systems worked fine after the  
update, but I'm not sure why on all my amd64 this happens and not on  
my i386 systems.
Is this because of the libc update being performed differently on  
amd64 and a lot of dependencies had to change? (if so, how would that  
affect binaries built from ports?)

regards,

Henno