I see that someone about says the same thing. After seeing that post and yours I have just tried to figure it our and can not. The song name is not clickable for me in the "now playing" window and if i click the upper right and go to the list of songs from the same album, and click the song name there, it restarts the song.
I am running beta 3 on an iPhone 5.
No doubt i just have not figured it out, so any further pointers would be appreciated. Usually with their software, things work as I guess they would. It is what so many of us like about it.