(Awkward) Silences II

I know we discussed awkward silences a long time ago on the first day of the semester, but I didn't really fully understand why we were talking about them until yesterday. I drive my friend home every day and yesterday was no different. We got into my car and started to leave school, and I don't know about him but I was feeling pretty spent after a week of studying for AP Exams so I just wanted to sit there and relax. Neither of us said anything for about three minutes, but then he starts asking about the most random things. For example, he asks if I've seen certain movies, to which I just responded with a 'yes' or a 'no', not bothering to elaborate any further. Then when I didn't expand upon my answer he asks different questions. Finally, after the barrage of questions seemed to be over, he asked why I was in a bad mood and if something happened at school. Then it hit me that most people really are uncomfortable with silence. I don't understand why he felt the need to constantly say something just to avoid the silence that I was trying to achieve. It was very obvious that I didn't feeling like talking, but I guess he just didn't pick up on that. And what bothers me also was that he thought I was in a bad mood. So just because someone doesn't feel like saying anything then they automatically must be in a bad mood, right?