A Trooper travels back & forth on Poncha Pass with instant on radar. Recently I was traveling southwest when I came upon a construction zone. I was going the posted limit when I noticed a new sign ahead of me that reduced the speed to 40mph. At that very same moment also saw a State Trooper coming towards me going the opposite direction. He blasted me with radar before I ever had a chance to reduce down to 40mph. He later pulled me over & told me I was speeding. I explained to him that I was going the correct speed limit up to the moment I saw the first 40mph sign & that I saw him at that same moment also. I had not reached the new sign at that moment either. He decided to give me a warning but told me to take my license plate cover off of my plate. The plate is perfectly clear!