Fancy Gap Area, Virginia Speed Traps

Going up the ramp at Exit 8 and merging into traffic in the slow lane. I pull over after less than one mile on the interstate and they claim I was going 83 mph, while merging into the slow lane. The merging lane ended where the Deputy was sitting. Deputy “cut me a break” and didn’t issue the reckless driving charge, “just the speeding ticket issued to everyone else”(exact quote). He also noted was from PA and could just pay the ticket online and not have to come back for a court date. I don’t know my exact speed but I do have trouble believing I merged into a slow lane that was doing 83 MPH!
Question: can a patrol car accidentally get a speed reading out the back instead of the front?

VA troopers love to set up in the median on I-77 from Fancy Gap all the way to I-81. Watch out for the emergency vehicle median cut thoughs; those are their favorite parking spots and with the hills, you can’t see them until it’s too late.