I was coming home from school today on a road that doesnt have any stores or door sensors. There was a line of about 5 cars behind me and 1 or 2 in front. All of a sudden I got an instant hit of 4 or 5 bars for about a second and then it stopped. It did this for about a half a mile on and off down the road. Could this have been a junk detector or what?Thanks.