When distcc is emerged, a new user is automatically created to run distccd. However, on my systems, this user has been assigned a uid over 1000, which is the "real" users range, not the system users range. This causes various minor negative side effects. The user shows up on the KDM login screen even though it is a non-login user (its shell is /bin/false). The user's email does not go to the catch-all email address for system users, if one has been setup. A new uid less than 1000 should be assigned for the distcc user.
I unmerged distcc, edited my passwd and shadow files to remove the distcc and distccd users (I guess distccd is from an old version), and re-emerged distcc. This time the uid was less than 1000. So it appears that this bug has already been fixed. Marking it resolved. Sorry for the premature bug report.