In the past few minutes, we've seen a shift "Up In Coupon" (Sometimes abbreviated at "UIC").  This can occur when there is tolerance for shorter duration coupons.  In other words, just like we saw when prepayment information came out saying that higher coupons (think 6.0's) might not pay off as quickly as anticipated, we are again seeing some of these periodic UIC pushes which leaves the top end of the MBS stack relatively unaffected, but pulls prices down on the lower end.

4.0's and 4.5's are now down 7 ticks each at 99-31 and 101-10.  5.0's are unchanged (still 6 ticks down on the day) at 102-10

UPDATE: now 2:06 EST, and no change to above price levels.