China distancing from Tehran?

I guess they can't get much more from Iran, what with sanctions and the limited and decaying nature of Iranian oil and gas fields (they are chronically underdeveloped and getting older).

Is this a sign of Beijing becoming more responsible as a global power? Or just them reading the writing on the wall?

I suppose as long as China has access to African markets, which are more varied and more prone to be influenced by Beijing and not be targeted by the West, there is no reason for them to be wedded to Tehran as much.