Mature/Experienced: What should I make of this communication lately from my ex?

He may simply have meant he was missing you as a friend. Maybe he's having some problems in his life. You've already said you don't mind being friendly, but don't see the two of you together. There may be too much water under the bridge for that anyway, since you have way too many differences. I wouldn't read much into it, unless he makes a serious attempt to get back together with you. No offense to guys, but a lot of them tend to go back to girls they felt comfortable with when life is otherwise rather quiet and boring to them. Guys see it as just going out and having fun with someone they know, but girls sometimes see it as a possible reconciliation. I'd just play it by ear, but not expect too much from it.