There's nothing quite like that feeling you get in the pit of your stomach when you just know that you've lost something important.

It happens to people all the time - especially travelers.

Some folks leave a favorite T-shirt behind in a hotel room. Others drop a set of keys at the airport.

Just ask, ahem, President Obama. Seems the big guy lost a magnetic presidential seal that was affixed to the side of his limousine as he wrapped up a fundraising visit to Philly on Thursday.

The seal flew off the side of the limo and whipped by motorists in the eastbound lanes of Interstate 76, where it was presumed lost . . . until shortly before noon yesterday.

That's when a veteran Philadelphia police officer found the seal on the side of the highway, near the Montgomery Avenue exit, while he was assisting the driver of a disabled vehicle, said Cynthia Wofford, the special agent in charge of the U.S. Secret Service Philadelphia field office.

"The officer was a part of the presidential motorcade the night before," Wofford said. "It was turned over, so it wasn't so obvious, but he found it for us."

Wofford said members of the motorcade saw the seal fall from Obama's limo as it traveled on the expressway.

A handful of law-enforcement officials tried searching for the seal in the darkness on Thursday to no avail.

"We're very grateful. It's in my office now, but it will be shipped back to Washington, D.C.," Wofford said.

The Police Department declined to identify the officer.

Obama's presidential seal has made the news at least once before,

On Oct. 5, 2010, as the president was addressing Fortune magazine's 2010 Most Powerful Women Summit at the Andrew Mellon Auditorium in Washington, D.C., his speech was interrupted when the seal on the front of the lectern clattered to the floor.

The president paused, peered over the top of the lectern, and said: "Oh, goodness," then added, "That's all right. All of you know who I am."

Daily News staff member Donald D. Groff contributed to this report.