The long term investment aspect may not be valid if the Republicans have their way. They don't want this program or any other Gov. subsidised plan. They will try to end this program during the Sequestration discussions. I'm concerned about a lower interest rate and the possible termination of the Trust [ as mentioned in BlackRock's Contingent Review Provision] if the Republicans are sucessful in winning this battle.
Same reasons bonds are selling off across the board, fear over this ever looming bond bubble and fear over rising interest rates. With a long-term investment like BBN these are just times to pick up more shares at a discount or let your DRIP buy them up for you. Maybe both!