after i upgraded 6.0 to 6.1, do i need to rebuild all of the ports i installed?

[lveax]

hey all.

i have a question about upgrade:

after i upgraded from freebsd5.4 to 6.0 in 2005,i got some error when
run a part of installed ports was installed in version 5.4,until a
committer tell me to rebuild all of my ports.

now i want to upgrade from 6.0 to 6.1 do i need to do this?

i have already got the source tag: RELENG_6_1 use cvsup,and i will use
it to upgrade to 6.1,is it right?

Thx