Sorry you feel this way but perhaps she had a bad day or maybe she's just another SA/clerk with attitude - nothing to do with your bag. For me, I usually have better service when I carry my blatantly more expensive bags.
if you don't have any proof, I don't think you should make a complaint. (eg. if her grandfather passed away, that might definitely cause her to be more agitated) Usually the manager will indeed ask you SPECIFICALLY what their employee did. If she had said something rude/descriminating, then that's a diff story. However if it's just her attitude, then lots of employees do this.
