Thanks for the responses.
Here's what we did:
We were actually low on cash, and we still had tolls to pay all the way to New Jersey. My husband was about to give him a few bucks, but I took out my last $10.00 and gave it to the guy.
All the while I was thinking two competing thoughts:
It's probably a scam. But you never know when you will be visited by an angel.
I did notice that he went immediately to the next car in the lot, whose driver wouldn't even roll down the window. I guess we will never know, but I am going to assume that if it was a scam, his bad karma will get back to him eventually.
There was no way I was going to give him my name and adddress, though.