Google's ui elements have a slight gradient and border to them giving them the appearance of an actionable element on the page..
My first thought was also that it's reminiscent of Google's UI elements. I think BootMetro does a better job (http://aozora.github.com/bootmetro/)
Windows Phone debuted in February of 2010, the Kennedization process didn't start until summer 11. Google's redesign was more influenced by Metro than the other way around.