Was this 'moonbow' positioned around the Moon, or was it opposite the Moon in the sky.

A true 'Moonbow' is a VERY rare thing to see, and will appear - just like a normal rainbow - exactly opposite the Moon's position in the sky.
Here's a 'Moonbow' - the Moon would be behind the photographer for this pic
Moonbow - Lunar Rainbow

If it was positioned around the Moon, then technically it was a Moon 'Halo', or 'Corona'
These are usually white, but occasionally you can see 'rainbow' colours - a beautiful sight.
A 'Halo' will always appear at 22° away from the Moon - if it is closer than that, it is called a 'Corona'
http://home.hiwaay.net/~krcool/Astro.../PA192767m.jpg

Check out this atmospheric optics site for details of more effects
Atmospheric Optics