Following this morning's first MBS buying operation, sellers were left holding the bag (or at least more bags than they thought they'd be holding).  That resulted in a bit of a fire sale in the past 20 minutes that took MBS down another 2-3 ticks (.06-.09), making for a total loss of 0.19 from the morning's highs.

A few lenders might see this as justification for negative reprices, but for the average lender, this is either too early to matter (many aren't out with rates yet) or simply not enough movement.