One article on FR said that not only was he offered a free plane ride out of Iraq, but trip to airport as well.
Here is the paragraph:
Michael Berg said his son refused a U.S. offer in early April to board an outbound charter jet because he believed travel to the airport was too dangerous. American soldiers refer to the airport highway as "RPG Alley" because of frequent attacks by insurgents firing rocket-propelled grenades.
According to the State Department, Berg told an American diplomat in Baghdad he preferred to travel on his own to Kuwait.
I would post the article from the Norman Transcript that contains local information about his time in Norman but it is not on-line and it is too long to type in this late at night!