Please help me understand!

This past Sunday I loaded up my explorer and headed back to campus from my home town of Excel, Alabama. I was driving down the road and I get on the interstate. Now you must understand, my explorer is a 1995. Therefore, I get nervous about it getting me back and forth on the interstate. My explorer being a '95 I do not go about 80 on the interstate (which yes this is still speeding, but still I know many people who go WAY faster than that). I set my cruise control on about 77. The trip is going well. I am listening to my radio and singing at the top of my lungs. Well I get to this point that is about 5 miles outside of Greenville, AL. This one car goes really fast and passes me. At this point there is a state trooper. Well I am in the right lane and I can not get over to the left lane, so I know that I need to get to the shoulder. I pull over to the shoulder. Well since the state trooper could not catch the person that passed me, he gets behind me. I am sitting in my car thinking "What..I can not be getting a ticket!" The state trooper walked up to my window and asked me if I knew why I was being pulled over. I told him I was speeding and I apologized for that. I gave him all the necessary cards and papers. He told me he was just going to make sure I was clear and I could go. That made me think I was not going to get a ticket. A few minutes later, the state trooper walks back up, hands my my stuff back, and also hands me a ticket! I was shocked! I could not believe I was getting a ticket for about seven miles over the speed limit. The state trooper then had the nerve to tell me to have a good day. Well I looked at the ticket and it stated that i was going 84 in a 70! This was impossible and I knew it. That moment was clear. His little radar did not clock me. It clocked the person that passed me. I did the right thing by getting on the shoulder because I could not get into the left lane. Since I did the right thing, I got the ticket. I called my my mom(I know it is wrong to talk on a cell phone and drive but I needed my momma) and I was so very upset. I told her everything. She knew that the ticket was injust. She told me not to worry about it, and she would be going to court with me. I get off the phone with her, and I continue driving to campus. When I made it to my dorm, I called my mom back. She said she talked to my dad. "Oh no" was my thought. I knew it was all over then. To my surprise, she said my dad did not get angry. She said that he knew about my explorer, and he knew I could not have been going that fast.
Now, I have a court date of October 20, in Greenville at 9 a.m. Sadly, I have to miss my math and biology classes to go to this court date. I am not happy at all. Luckily, my parents are going to meet me there so they can go to court with me. If I still have to plead guilty, my parents said I could go to a driver's class and the ticket would basically be erased. This fact settles me a little bit. Still no one really understands why I am so upset. I am upset because this is my very first ticket. My personal record has been violated forever.