is a Bond Bubble Even Conceivable?

Spencer of Angry Bear says not:

BOND BUBBLE?: Many are talking about the bond market being the latest bubble. But it looks more like the press is just seeing bubbles everywhere. To me a bubble happens when everyone starts believing something that probably is not true... that the long term earnings growth of the S&P 500 was shifting up.... In the 2000's bankers and home owners came to believe that housing prices could never fall so that homeowners could always refinance their...