Weird situation which is kind of hard to explain...
I've had my 2.0 Touring since February and noticed this issue not long after buying the car. I haven't had the time to take the car into the dealer but now with a recall due I may have them look at this at the same time.
I'll be sitting at a stoplight, traffic, etc., at a complete stop, transmission in drive. I'll be behind a car which has rear parking sensors in the bumper which is also completely stopped. Sporadically, my parking sensor's proximity alert will come on. In most cases, neither me nor the car in front of me moves an inch and the alarm will stop without any movement of either vehicle. Occasionally, the alert comes on and off briefly, repeatedly, in a single instance. I'm rarely stopped long enough for it to be that much of an annoyance (part of the reason I haven't made time to get to the dealer) since the traffic light changes or traffic starts moving. The one constant is it only happens when I'm behind a vehicle with parking sensors in there rear bumper, if there are no sensors in the car in front of me it never happens.
Anyone else ever notice this happening with their Accord?