I think that the DEA guy recorded Tara talking about it and turned her in after his route with Otto failed.
That's a great point. He could have easily put a bug in her office when he was in there by himself.
Things I want to see next season:
1) Phil either do something relevant or get killed off. He just doesn't fit.
2) Happy get unleashed on someone.
3) Lincoln Potter return to the story
4) Otto finally put out of his misery.