That's kinda funny. Similar thing happened to me last week. In an ambulance, no less. we're sitting at a red light (non-emergency) when an old guy in front of us got out of his car and started shaking his finger at us. Windows were up so I couldn't hear what he was saying. Did this for a minute, then got back into his car and took off when the light changed. Again, non-emergency response (moving the unit to cover another station), not tailgating, not close to him. Only thing we could think of was my partner (driving) was looking at his phone. But, we were stopped. So, no idea what ticked him off.