The Australian clocked 51.70 seconds to finish fifth at the Prefontaine Classic grand prix meeting in her first international 400 metres since the 2000 Sydney Olympics.
"It was a little disappointing," Freeman told reporters after she was more than two seconds behind Mexican winner Ana Guevara's season-leading time of 49.34 seconds.
"I don't think it is any indication of what kind of fitness I'm in," said Freeman, who has run 51.66 seconds this season. "It was just one of those days where you are not quite on it.
"I would like to have run a qualifying time for the Australian world championships team as an individual runner, which is 51.6,
Freeman will spend a few more weeks training in the San Francisco Bay area before going to Europe for what she hopes will be a competitive season there.
"I am going to go away now and try to settle down and try not to get too worried about things," she said.
"I still love running and I still love competing. I was just happy to be here."
Guevara, the undisputed favourite to win the women's 400 metres world title in Paris in August, said she was delighted to see Freeman competing again.
"I am very happy for her," said Guevara, who gave Freeman a hug after their race.
"I hope she can run very well over the next year and in the (2004 Athens) Olympics and it will be a close race."