Security Lady @ Store Treating customer like *****

I quickly pop into Edgar's Boulders as I do twice a week and saw they had a sale on. I go there for the last two years, sometimes more than twice a week as I just work across the road. I know that most retailers have a rule to search you goodies bags that was purchased, but today I felt like I was treated as a *****. As I walk out, and the security lady at the door insisted that she wants to look in my personal bag, without any reason, but let all the other customers walked out of the store. I confronted her and asked her so you just randomly stop people and ask them to search their bags? she had such an attitude and said she has the right to search me, again I ask her and she just reply, she will search people. Its just disgusting to treat loyal customers like that, I will never put my foot in that store again.