The above charts of the municipal bond market, mortgage, junk and investment grade corporate bond markets all indicate money is flowing into the dent markets; it's not just the Treasury market that is benefiting from the recent move into fixed income.
The question now becomes are these markets in the middle of a bubble? The MUBs are right at crucial support and the MBBs are just below support, indicating some technical weakness. the LQDs have sold off a bit, but still have some technical support.