Mortgage rates fell modestly today, but remained well inside the narrow range that's been intact for more than a week.  For most lenders, that means conventional 30yr fixed quotes of 4.0-4.125% on top tier scenarios.  Most borrowers will continue to see day-to-day changes in the form of minor adjustment to upfront costs.  

Narrow ranges in financial markets speak to indecision or an unwillingness to take too much of a stand ahead of potentially important developments.  In the case of the current narrow range (which affects stocks as well as bonds), markets may be waiting for one of several big-ticket events in the coming days.  The most immediate possibility is tomorrow's Fed announcement.  While the Fed isn't expected to  raise rates at this meeting, traders will nonetheless be scouring the verbiage for clues about the Fed's next move (possibly at the June meeting).  

In terms of locking and floating, a narrow range ahead of big-ticket events means higher risks and greater rewards for floaters.  In other words, if you roll the dice and win, the payoff will be meaningful.  But if you lose, the first move higher runs the risk of being bigger than a typical move higher.