Guy Trying to Help...Feeling Unnerved by the situation. Would like perspective please.

Sorry if this isn't the right place to post this but I wanted to get some thoughts on this cause I'm still feeling a bit weird about it.I was driving a rental at about 7 pm tonight and someone starts shining a flashlight into my face. I turn to see where it's coming from and it's the car besides me. There's a middle age guy who just stares at me and points to the front of the car and looks super mad.My initial reaction is that I'm in his lane or something but I'm not. And I look back and him and he just looks angrier so I ignore it because I am kind of creeped out that he's going to come out of the car. He does the flashlight thing again and gestures to roll down the window while he points again and I do it. I don't know why but I just want him to leave me alone. "TURN ON YOUR LIGHTS BEFORE YOU KILL SOMEONE!" and he's REALLY angry. "uhh...thanks." Yeah driving a rental and am normally used to auto headlights. whoops.A part of feels really mad that he had to do it like that but it really made me feel like it was going to be a bad situation. Did he think the first way was the best way to approach it?Then I feel like I'm a jerk who was too paranoid and should be thankful cause I could have gotten a ticket. Why am I assuming that just because an older guy is trying to talk to me is going to be assault.