Are you sure about that? I have the EX too and it does beep once whenever it's put into Reverse, and the rearview camera activates. Perhaps you have the radio volume up louder and you don't hear the faint beep?My EX V6 doesn't beep when I put it in reverse, only if something is behind my truck, like when it's in the garage, there's 'stuff' behind it, about a foot away from the back of the truck so, it beeps. But if I'm out on the road and put it in reverse, no beep because nothing is behind me.
Yes I had the same thing a few times during the winter. Anything covering the sensors can cause a false reading as the sensors are ultrasonic and rely on sound waves bouncing back to the sensors.I also found out that even a very thin coating of ice (can hardly be seen) can cause false sensor alarms!