Caught by the old dreaded traffic violation stop! I suspect they were hit with the "Well, if you don't have anything to hide..., you won't mind if we search your vehicle" routine. That, or the "I smell weed" routine. Guessing they succumbed to the pressure and gave them permission to search.
I notice they weren't charged with any traffic violation according to the purple tie squad news release. I wonder why, - or were they just cutting them a break?
Avenue D in Rochester is one of those streets you drive down very quickly with windows up and doors locked. Still don't support phantom traffic stops and arrests for simply possessing a handgun though.