Borrowers who thought they’d seen the last of 30-year fixed mortgages with interest rates below 4% got a pleasant surprise this week, as stock market selloffs, fears of another world-wide economic slowdown, and perhaps an Ebola scare helped drive down mortgage rates to their lowest levels in more than a year. Interest rates on the 10-year Treasury note have fallen to 2.55%, down from 2.61% a week ago, leading to some 30-year fixed mortgages dipping below 3.99% for the first time since June 2013, according to Bankrate.com.

“We have seen a flurry of activity in the last 24 to 48 hours,” said Mark Livingstone, a mortgage broker at Cornerstone First Financial in Washington, D.C., who said the sharp fall in Treasurys has potential borrowers heading back into the market. “Everything has come down and we’re expecting it to come down a little bit more,” he said.

The drop in interest rates has corresponded with an increase in mortgage loan application volume, the Mortgage Bankers Association said Oct. 8, with its Market Composite Index increasing 3.8% for the week ending Oct. 3, from a week earlier.

MBA’s Refinance Index rose 5% from the previous week. It was the first increase in three weeks, MBA said. The average contract rate for a conforming loan ($417,000 or less) on a 30-year fixed mortgage for the week ending Oct. 3 was 4.3%, down from 4.33% a week earlier, MBA said.

For contracts greater than $417,000, or most jumbo loans, the rate decreased to 4.21% for the week ending Oct. 3, down from 4.28% a week earlier, MBA said. FHA loans through Oct. 3 dropped to 4%, down from 4.07% a week earlier. The MBA’s survey covers about three-quarters of all U.S. retail residential mortgage applications.

A “parade of horribles” has driven down Treasury yields amid an equity market selloff, says Mike Fratantoni, chief economist with the Mortgage Bankers Association. “It’s a very strong flight to quality,” he said.

Those negative sentiments have been able to outweigh a strengthening U.S. economy, better-than-expected unemployment and GDP reports that were expected to help push long-term interest rates up, Fratantoni said.

Should mortgage lending standards ease?

Still, it isn’t expected to last long—and that may mean only borrowers with rock-solid credit will be able to take advantage. “For those who can qualify, it’s a great opportunity,” to get into the mortgage market, said Anthony Hsieh, chief executive of LoanDepot.com, a Foothill Ranch, California-based mortgage lender. But because of what he considers overly tight credit standards, Hsieh doesn’t expect many Americans will be able to refinance successfully before rates begin rising again.

“It’s a blip, but it’s a nice blip,” says Livingstone. “Everybody’s enjoying it like Indian summer.”

Livingstone expects that rates could be up as much as a point within a year, especially as the Fed tapers off its purchases of mortgage backed securities (MBS). “Now that the Fed is no longer buying the MBS, the yields need to go up” to make them attractive to private buyers, said David Stevens, president of the Mortgage Bankers Association, in an interview.