In the wake of the bond market’s impressive rally during the past year, some experts have called it a bubble.

Star economist David Rosenberg disagrees.

“I find it truly amazing to see how many pundits refer to the bond market as ... a bubble,” he wrote in the Financial Times.

“How can a security whose price is constantly projected to decline by the economics community be in a bubble? How can any asset class be in a bubble where the capital is guaranteed and which pays out a coupon twice a year?”

Only 6 percent of U.S. household assets are in bonds, so it makes sense that aging baby boomers will buy more as they seek safe investments for retirement, says Rosenberg, chief economist at Gluskin Sheff & Associates.

Inflation, now 2 percent, is the key indicator for Treasury yields, he says. And bond-bubble heads are looking for a surge in prices.

But that’s not the real threat. “Deleveraging is the new secular trend,” Rosenberg wrote. He anticipates deflation of 2-3 percent.

“(That’s) enough to take bond yields back to their 2008 microscopic lows.”

Pimco Chief Investment Officer Bill Gross has turned bullish on Treasuries too.

“The U.S. is the least dirty shirt,” he told Bloomberg.

“The world is full of dirty shirts in terms of excessive debt, and the United States is one of those countries, but it still remains the reserve currency and still remains the flight-to-quality haven.”