I did some research and found that it is a bug. Post #5 here shows how to fix it but it may get over written after an update.
The bug is listed for Ubuntu on Launchpad as
CPU Frequency Scaling Monitor asks for authentication all the time.
An overview of mc4man's workaround is to:
Carefully edit the file:
gksudo gedit /usr/share/polkit-1/actions/org.gnome.cpufreqselector.policy
Scroll to the bottom of the file and change only the parts in red:
Thanks for the workaround mc4man!