The Mystery of the Yellow-Green Truck

Today was downright warm compared to what has been happening here in Indiana lately. It was 40+ degrees, so of course we went for a ride. We took the abandoned railroad line near where we live. There is still quite a bit of snow on the ground, so we took it slow and easy. The railroad line is about 4 miles long, and roads intersect it along the way. After passing one of the intersections, I happened to turn and look back and noticed a yellow-green pick up truck sitting in the road. I just knew whomever was in the truck was looking at the 4 of us on the trail. I asked John if he noticed the truck, and of course he didn't. So not thinking much more of it, we continued our ride. We eventually turned back and headed for home. We were off the railroad line and almost to the lane that leads to our house. We were passing the home of one of our nearest neighbors, and got off the horses to walk them the rest of the way in so they could cool off. I looked back, and there was the yellow-green truck again!!! It was going very slowly down the lane. I told John, "There is that truck again!!!" He turned to look, and then the truck turned into the driveway of the neighbors house. I thought, "Oh, they got a new truck....it must have been them...they saw us riding and stopped to check us out." But then, the truck backed out of the driveway and drove off in the opposite direction. Something strange is going on here. The person in that yellow-green truck was following us -- of that I am certain. Why??? Very, very strange, and kind of creepy!!!