Problem with Path/Ports

Newbie ports question.

I'm been running 6.0 for several months with no issues. Suddenly, 
installing any port fails with this message:

/usr/local/sbin/pkg_info: not found

pkg_info and pkg_create are both in /usr/sbin.  The $PATH in the shell 
is correct and hasn't been touched. pkg_info works fine from the command 
line.

What's the correct way to fix this? How might I have broken it? The last 
thing I did was cvsup about a month ago,
but I'm pretty certain that I've successfully installed ports since 
then. Any help is greatly appreciated.