He probably felt sorry for you, seeing, what appeared to him, as a little old lady creeping along the road, loaded down with shopping and drenched by the rain.
I would never, ever, accept a lift from someone I did not know.
When I was in my early teens by sister and I were walking to church when someone stopped and offered us a lift. I hesitated, the driver looked vaguely familiar and he had his wife and childwith him, but I and my sister resolutely said 'no'
When we got home, he was with my parents. He was a new neighbour and he had called in to tell them what had happened and apologise because he said, he should have realised we would not know him - and all so to commend my sister and I for our behaviour in resolutely refusing the lift.