Strange error message but other than that I believe this is expected behavior.
Mac OS X is designed to be a multi-user system. There will be one admin account and many user accounts.
Even when the machine is owned and used by a single person, best practices for security recommend that the admin account is not used day to day. A normal user level account is recommended for day to day use.
The OS includes mechanisms which allow applications to request authentication credentials when an operation requires admin authority. Surely that is the proper response. It knows that it will require a high level of authority before it begins. It can request authentication, if the authority cannot be provided, it can stop with an appropriate message.