Mountain Lion Mail new message in thread scrolling

Trying to eliminate an annoying new behavior in Mountain Lion's Mail. After receiving a new message in a thread/conversation when I click on it to read it, the thread always opens in the viewing pane scrolled to somewhere in the middle or another random location in the list of messages, rather than the top where the new message is.

This has made it disorienting when following a conversation, because I keep seeing older messages first when opening a newley received message. This is especially obnoxious when the messages are long and it takes a while to scroll to the top to see new message.

Is there a setting somewhere for this? Is it a bug? Can I have my old Snow Leopard Mail back? I haven't found any other reports of this behavior.