Sam has a long way to go yet, but he's getting there. IDK, but I think he's just being what he is, the Younger Brother. He wants to be treated as an equal but it's not easy for Dean to let go of a lifetime role, and especially not after what happened during season 4. The hurt is still there for one thing yet at the same time he knows what would happen if he let Sam go, so yeah, the ... balance, for want of a better word, is still not there fully.

Dean apologizing, I didn't like that either, but again, I think he was being the Older Brother there, what the people in my part of the world would say as "giving way", if you know what I mean.