Sure could be air. Look around for leaks. If you see none,
then try the "purge air" procedure described below:

With the car off, and the power steering reservoir full,
take the steering wheel and turn it back and forth 50 times.
Again, with the power steering reservoir full, get a friend
to standy by with a bottle of power steering fluid as you
start the car.  The pump will suck down all the liquid in
the reservoir into the system.  It is CRITICAL that the pump
not suck air into the system. Start the car for 1 second and
shut it off.  As the level goes down have your friend add to
the reservoir.  Repeat as needed until the reservoir level
is filled appropriately.  When done, replace the reservoir
cap, start the car, and twist the steering wheel and listen
for "squeeling".  As long as none is heard, you're fine.
Again, it's important to keep air out of the system.

From http://timingbelt.soben.com/ , near the bottom, as part
of the procedure for re-installing the power steering pump
etc. after replacing a timing belt.

I used the above for my 91 Civic a few years ago when
replacing the timing belt. I sure heard noise at first. The
above remedied it.

Use only genuine Honda Power Steering fluid. I bought mine
from a place like Autozone. Arguably the stuff marked
"genuine Honda" etc. there is not good enough, but I have
not had problems in the three years I've used around a
bottle of it. Your Honda dealer should sell genuine OEM
Honda PS fluid, and it does not cost all that much more.