You're right, Silentspace, as I knew you would be. I had thought you could retreat w/o provoking an AoO if you retreated directly away and thus didn't move through any threatened areas. Upon reviewing the SRD, I see that this is not so. (did this change in 3.5?)
Manzanita could have taken a 5 foot step back and cast her spell w/o provoking an AoO, couldn't she have? Or she could have done a withdraw, which is a double move, but no attack.
In retrospect, her goal was to cast her spell and avoid an AoO. She should have simply taking a 5 foot step away and cast.