All CFIs are instrument rated. You must hold an instrument rating in
order to apply for a CFI certificate. The FBO probably simply meant
that the CFI was not an instrument instructor. That's no big deal. Many
CFIs who are not CFII's spent lots more time in the clouds than actual
CFIIs. For a private pilot, I wouldn't worry too much about him not
being an instrument instructor (but remember, he IS an instrument
pilot)

-Robert, CFI