Mortgage rates were sideways to slightly lower today, keeping/bringing them in line with the lowest levels in roughly 2 weeks (depending on the lender).  Interest rates in the broader bond market were slightly better off, with 10yr Treasury yields falling to the best levels since early February.  

While it hasn't always been the case (especially during the mortgage meltdown), the 10yr Treasury yield (the rate the US government pays on the money it borrows for 10 years) correlates with mortgage rate movement extremely well.  Think of Treasuries like a person holding a leash, and think of mortgage rates like a reasonably well behaved dog on the other end of that leash.  The dog may tug or lag behind, but he/she's generally not far from master's side.  

In the current case, the dog is lagging the master to a small extent.  In other words, mortgage rates haven't returned to previous lows as quickly as Treasuries.  That may not be the greatest news for today's mortgage rates, but it means that there's room to improve if Treasuries are able to keep the recent trend alive.  Looked at another way, the absence of improvement means mortgage rates could be better insulated in the event the broader rate market moves higher tomorrow and next week.

All that having been said, we still haven't seen resounding evidence that rates can move lower in a big, meaningful way so far in 2018.  That's not to say it couldn't happen--just that it hasn't happened yet.  As such, mortgage rates at 2-week lows present a good opportunity for those hoping to lock in at slightly more favorable terms.  After all, "slightly more favorable" is just about the biggest victory that's been available for prospective mortgage borrowers so far in 2018.