"Not in sudoers file" error message is misleading

I recently bumped into a bug that removed me from the admin group, and noticed that due to sudo giving me the error "user not in sudoers file". That made me realize that the error message is slightly misleading, in which it induces the user to adding his name to /etc/sudoers instead of the more correct (at least in Ubuntu) procedure of adding his name to the admin group and leaving /etc/sudoers untouched.

The message should be changed to something that advises that the user should be in the admin group, and the admin group on its turn should be in /etc/sudoers.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: sudo 1.7.4p4-5ubuntu7.1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
NonfreeKernelModules: nvidia wl
Architecture: amd64
Date: Sun Jun 26 21:41:58 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcEnviron:
 LANGUAGE=fr_FR:en
 LANG=pt_BR.UTF-8
 LC_MESSAGES=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: sudo
UpgradeStatus: No upgrade log present (probably fresh install)