The Omaha World-Herald reports that the 67-year-old Duke was taken by a private vehicle last evening to the Nebraska Medical Center after complaining of stomach pain.
Organiser Bruce Crawford says Duke's medical condition was not serious, but that an Omaha doctor who had been running tests on Duke asked her to come in for more tests last night after she reported the pain.
Before seeking medical attention, Duke delivered a speech at Omaha's Joslyn Art Museum, where "The Miracle Worker" was shown. The movie tells the story of tutor Anne Sullivan's efforts to help a young Helen Keller who was both deaf and blind.