That is, a speed trailer that has never been in that particular location before.
Coming home from work, I stopped at a traffic light near my house. Shortly before I reached the light, my V1 was starting to brap out a K band alert ahead. While I was waiting, I happened to glance down at my (still-quiet) STi-R+, and noticed the satellite icon was spinning, which is strange because I don't ordinarily get an alert in that location, except maybe once or twice over a month ago caused by one of those stupid adaptive cruise controls on a Mercedes.
Anyway, I unlocked it manually and it alerted normally after that (it was K, 24.122). But why did it see fit to lock out this signal when it was never there before? I know it's supposed to autolock after approximately 3 times seeing a signal, but does that include seeing it only 3 times over the course of 2 months? Plus I doubt the frequency was the same, since previous K hits were from adaptive cruise controls, and this was a speed trailer.
After I got through the light I drove on to see where the trailer was, and it was about 1/4 mile from the light facing the opposite direction, so it was forward facing relative to where I was when my V1 started "seeing" it.