I was sitting at an intersection that usually has a weak K-band false from a set of doors. The light was red and I was first in line. I started to pick up a weak X-band signal. I figured it was from the strip mall up the road, but it grew stronger to full alert. Then, I see an unmarked LEO pass through the intersection. Then, the signal ramped back down. That definitely caught me by surprise! I didn't know they still used X-Band. This was in Ft. Myers, FL by the way. I will definitely be more attentive to X-Band warnings now!