I was selected for secondary screening as I'm brown, was traveling alone to a muslim country high on the so called terror list, and had stayed there for two months. From my experience this is common for USC who look like me and spend longer time periods in certain countries in the middle east. They asked me what I did for work, what i was doing in that country for two months, asked me questions about my family members, personal life etc etc. It was quite annoying actually and I didn't respond honestly as I felt that it was none of their business but just now realized that it could possibly cause trouble for us in the future.
She didn't have to go through secondary screening only I had to.