Nothing dramatic is happening by any means, but MBS have trickled down to new lows for the day. 5.5 coupons are still up 1 tick (.03) but down 5 ticks (.16) from the highs. Lenders who priced near those highs could technically justify a negative reprice.
10yr yields are also at their weakest levels, now up 0.4bps at 4.217.