MBS is falling again.  We're only down an eight off the highs, but nonetheless, this may prompt some lenders to take that eighth away from you if they already released rates this morning.  Personally, I would give up this eighth (if it even happens) in order to see what the market is doing later today and tomorrow.  But if pricing right now looks great to you and you can't afford to lose any ground, be advised that some lenders might reprice.