From the replay, it showed one of the American players storming the box when the penalty was taken, which makes a bit more sense, at least. Which would mean Hope Solo got the yellow for expressing her distaste for the call.
While that would still be extremely harsh, I can at least live with that decision, if that's what it was.
--
Xbox GT/PSN name: TatteredUniform
http://img.imgcake.com/craterbuttonsgifus.gif