What if the guy I'm dating talks about other women or past experiences with dating other women?

The guy I'm dating has brought up past dating experiences, on a couple of occasions he's mentioned his ex. It sounds like she did a number on him, because they broke up a couple of years ago and she STILL come up in conversation. For example, we were talking about weird dreams we've had. In one dream, he was making out with an actress (it's normal, I get it). Then he started talking about dreams about running and hiding from his ex. Also (back when they were together) about when he had a dream that was a realization that he loved her. This conversation started off as talk about crazy, vivid dreams and turned into...that. I really feel like he's still bitter about the end of their relationship, but does that mean he's not over her? He says he wants nothing to do with her and will avoid her at all costs (they have mutual friends). Should I be worried? Is this normal to bring up the subject of past relationships (like he's comfortable with telling me everything) or is this a sign that he's really not that interested in me?