I have had the same, Paul.
This time it was a man who saw a Jaguar parked in Blue Badge badge bay and while I was queueing at the ATM observed that people who have Blue Badges should not have a car like that.
Keeping my face straight, I observed that he or she was probably a pensioners too, and they should not be allowed to drive cars like that. We had a jolly little conversation and I was egging him on a bit, as he made a few suggestions as to what the Government should do about it.
He was rather surprised when I waved to him as I passed him while driving out of the car park!