Mortgage rates dropped today. It wasn't a huge move, but they didn't have to go very far to get to the best levels of the month. To be fair, many prospective borrowers are still seeing the same interest rate at the top of a loan quote that they would have seen any time in the past 2 weeks. In those cases, it would simply be the upfront costs that moved down.
As for the motivation for the move, underlying bond markets had a good day thanks to an economically downbeat press conference from the European Central Bank (ECB) and weaker-than-expected inflation data in the US. The ECB doesn't dictate rates in the US any more than the Fed directly controls mortgage rates. But they do set policies that have a big impact on European bond markets which, in turn, have an impact on the US bond market. And the US bond market definitely has a direct impact on mortgage rates.
Bonds also cheered the tepid inflation data, or rather, bonds didn't move into weaker territory--something they might have done if inflation was higher than expected. In general, bonds hate inflation because bonds earn a return based on today's dollars and inflation makes future dollars worth less. In other words, more inflation means interest rates would need to go higher in order for investors to get the same return on investment. The bottom line is that stable/low inflation is neutral/good for rates.
There are still some risks on the horizon from things like a potential US/China trade deal and an amicable Brexit agreement (both would help the global economy and a stronger economy = higher rates, all other things being equal). Otherwise, today's bond/rate improvement is the best indication we've had in 2 weeks that rates can continue operating in the new, lower range achieved in late March.