I was driving South on I-35 and noticed three lights in my rear view mirror. The lights were on top of each other, two bright lights with a smaller one in the middle. I thought at first it was a big 18 wheeler with lights on only one side - maybe burned out on the other side - and I remember thinking the 18 wheeler must be HUGE because the lights were so big - and high off the road. The road was illuminated in a triangle in front of it, like it was shining down to a point. It followed me for about five minutes, maybe longer, and I kept looking in my rear view trying to figure out what it was. It was so smooth it didn't seem like it was really moving, I kept thinking maybe it was a reflection of something - but then I'd think no, can't be, because it's lighting up the road ahead of it. I saw the tail lights of two trucks up ahead and was relieved, I am not sure what I thought but I was glad to see the tail lights. I looked at least once and the lights were still there and then...they were not there. Just like that. Gone. I thought I should call someone, my husband, my daughter, my best friend, and tell them I just saw a UFO. I can't explain why I didn't even tell my husband when I got home; I didn't tell him until the next day. And I forgot to tell him about the light on the hiway coming to a point. Weird.