One caution I would give readers is that a driver can't know whether it is a good cop or bad cop at inception, so there is always risk when notifying the cop. We've plenty of reports of guns being temporarily seized and the serial number run.
Also, the experience of the OP proves the lie from all those cops who justify temporary gun seizures by saying drivers with guns are dangerous, including the US Supreme Court in PA vs Mimms. If all drivers with guns were dangerous, or even a significant number of drivers with guns, no cop would do what Officer Meth did. Cops would temporarily seize all guns every time.