It's apparently been scientifically proven that people remember other details about another person better than names. Therefore, it's not strange at all that you'd have trouble remembering them.
I personally remember faces and details well, and will sometimes recognize someone even if I only talked to them once, briefly, months ago. However, when it comes to names, unless the person or their name somehow interests me, I am capable of forgetting it within a very short amount of time. I know very well that I am not the only person who is this way, so this does support what I wrote above.
In other words, I don't think it has to do with being a sociopath, but rather just the fact that the brain associates faces and details with people better than a name.