Interesting. I had an A4 B8 that did exactly the same. If I waved the key fob past the OSR corner of the car, the boot lid sprung up of its own accord. It was still under warranty (just), sot he car went back to the dealer several times, without success. The best they could offer was to line the inside of the bumper area with tin foil to block the signal, or to deactivate the advanced key.
The factory didn't have a solution, & eventually Audi took the car back, as I wasn't prepared to accept the tin foil solution.