K Band Speed Sign

My local PD just put up a K band speed trailer on the street right next to me. I drive by a few times a day to test my distance. 8) Anyway I put my V995 in tech mode to try it out because I never used it before. It came up 24.158. I went home turned of my RD and when I went past it later that day it came up 24.150. Is there any reason for this? Can the frequency of the radar gun on the trailer change? Or is the tech meter feature just a bit off? I got pretty good results on my V995, I'm happy with it. The radar gun would start on K at about 2 bars when I got near the street, and when I got almost lined up in front of it, it went up very quickly. It almost reacted like an instant on. I guess because the street is on a curve and the signal increased very quickly once the line of sight was better.