MBS are down a quick eighth of a point from the most recent highs.  Unless a lender repriced for the better at those highs, negative reprice risk is minimal and, indeed, not at all justified by this amount of movement (i.e. this is a "heads-up" alert simply to explain the jumpiness. 

While the official early close is still one hour away, the cut-off time for most large traders is/was 1pm ET. There's been a typical surge of volume around that time. A quick jolt of several bps in 10yr yields is not uncommon.  There is no underlying fundamental motivation. It's all a byproduct of last-moment year-end position squaring.