On team orders Webber turned his engine down. The team instructed Vettel to turn his down too but not as much. Of course he couldn't defend or race Vettel. He had less power. Red Bull have confirmed Vettel hadn't turned his engine down as much as Webber had been instructed to.
Just like Turkey in 2010... Webber was told "conserve fuel" and Seb was on him like white on rice... which lead to the start of their ... ah.... friendship ? ...