Just as we predicted, Robert Redford had his sitdown yesterday with Fidel Castro. "He came to me," the actor said in Havana. "He seemed in good health, good humor, good spirit. Castro stopped by the Hotel Nacional to talk about "The Motorcycle Diaries," the movie Redford produced about Che Guevera's nine-month bike trip through South America as a 23-year-old medical student. He also showed it to Che's widow, Aleida March, who said the movie was "excellent."