However, he failed to mention that he had a handgun in the SUV, which he was required to do by law, the source noted.
The cops took the gun, which is registered to a man who lives in Philadelphia, the source said.
Harrison was not charged with any wrongdoing and was allowed to leave the scene.
The source said the officers asked Harrison to come in for additional questioning, but he declined. He wasn't required to come in by law.
The weapon might be test-fired by investigators to determine whether it may have been used in two prior shootings linked to Harrison, the source noted.
For much of the last few years, Harrison has generated more headlines for his alleged links to the shootings than for the outstanding skill he once displayed on the football field.
Local resident Dwight Dixon claimed that Harrison shot him in the hand on April 29, 2008, after the two fought near Harrison's garage at 25th and Thompson street in North Philly.
Another man, Robert Nixon, claimed he was wounded in the back by an errant shot fired by Harrison.
Police later said ballistics evidence proved that several shots had been fired that day by a gun Harrison admitted to owning.
Charges were never filed, however, because then-District Attorney Lynne Abraham said Dixon, Nixon, Harrison and several others told numerous contradictory stories about the shooting. Dixon and Nixon filed civil suits against Harrison.
On July 21, 2009, Dixon was riddled with gunfire on Girard Avenue near 28th Street, two blocks from Harrison's bar, Playmakers. Dixon told police he believed Harrison was behind that shooting. Dixon died two months later. His slaying remains unsolved.
Earlier this year, District Attorney Seth Williams said Harrison was a "person of interest" in the case.