Watching top, i notice some gcc instances run under the portage user and
others under the distcc user - is that normal?

The gentoo distcc wiki page states "If compilations should also occur on
the local machine, put localhost in the hosts list. Conversely if the local
machine is not to be used to compile, omit it from the hosts list." and to
me that implies that all compilation is via distcc once its in FEATURES, so
i'm surprised to see jobs running as the portage user.