I saw it, and it was DPI all the way. If you get a chance to watch again, watch the defender's feet. He is slightly ahead of Johnson and to the left, then as Johnson starts to pass him, he moves right, getting directly in Johnson's path - THAT is where the DPI happened (and no, he wasn't looking back yet). Johnson's push did look bad, but he was merely fending off a player that moved into his way.