I just got notified for 3 "supposed" non-pays and got me by photo. Called the EZ Tag store and they said the A4's body style or electronics on the windshield (dimming mirror / compass I guess) sometimes causes the "scanner" to not read the tag. They're sending a small barcode for the front plate to replace the tag on the windshield. FYI for others that may come across this.

till they said where I need to put it. Ah well, maybe it'll keep me from "breakin 'da law, breakin' da law"