As a pharmacist, I NEVER let my techs be that rude to someone. Yes, there are some times that I will call the doctor in order to verify that it is legit. I do this only when the person has a history of abuse (i.e. consistently asking for refills of controlled substances early or bringing scripts or calling in a new prescription for a control after hours. I will only fill them at the most three days before the patient will run out.
As far as the technician... it absolutely is NOT her place to make those assumptions about a patient. If she had any suspicions about the history of your med profile, it should take it to the pharmacist. And she should absolutely NEVER confront you about it. Also, it's strange that she wanted to call and verify your promethazine prescription considering that it is not a controlled substance. It's not her place to judge. Definitely complain.
Just a side note. I absolutely loathe Walgreens. I almost went to work for them once I was licensed. I've never had good service there.
I am very sorry that happened to you.