Going To

We worked on the future tense in class tonight. Students had to write sentences by choosing the ending that made the most sense and adding it to the correct future form. More than one student created this combination:

I have a headache. I am going to major in psychology.

Why not. The form is correct, and under the right circumstances, it makes a lot of sense.

Question

Is it normal for a post office worker to ask: "What are you sending today?" The woman working at the branch near campus asked customer after customer -- and they all answered! Am I correct in thinking that our mail is private? I wanted to say, "None of your damn business!" when she asked me, but instead said, "Something for my dad." Help me out. Is this being asked from branch to branch or is she just nosy?