I only notice now, since upgrading to 4.0, that I can't seem to locate my forum rules and disclaimer.

Whereabouts are they located on 4.0?

When you edit a forum:

Found that.

Have my list of rules from 3.x not been kept after the upgrade?

If it's not there, then you should report a bug: https://community.invisionpower.com/4bugtrack/active-reports/