Most Helpful Guy
You guys werent even in a relationship, so how can he be you ex?
Most Helpful Girl
If I were you, I would mention it in a joking type of way. You don't want it to appear that you are hurt because he blocked you (even though you are).
It sounds like he is a player and by you being around on his page and viewing his comments, he may think that you are basically blocking his chances on getting with other females on his page.
Doesn't make much sense for a guy to block, unless you are constantly on there snooping and commenting all of the time.
Overall, I think that he likes you but he doesn't want anything more than what you guys currently have at the moment. Bottom line is he's a little player... Treat him how you everyone else.