It could mean a couple things..........Sometimes when we dream of other people, the feelings we receive from them, are actually how we feel about ourselves.........."projection".
Sometimes when we dream of other people, it is the other person's Soul connecting with our own.........
I would interpret it depending on what you want in real life with this person. Is this really someone you really want to get back in touch with? Or is it just a fantasy that you know will never happen? Perhaps it is a means of closure for you, that you both are at peace with one another?