BILLINGS, MONT (AP).- Frayed, torn and maybe even a little bloodstained, the only U.S. flag not captured or lost during George Armstrong Custer’s “Last Stand” at the Battle of Little Bighorn sold for $54 when it first surfaced in the 1890s. On Friday, the swallow-tailed 7th U.S. Cavalry flag, known as a “guidon,” is expected to bring up to $5 million at an auction at Sotheby’s in New York. And while Custer’s reputation has risen and fallen over the years — once considered a hero, he’s regarded by some contemporary scholars as an inept leader and savage American Indian killer — the guidon has emerged as the stuff of legend. “It’s more than just a museum object or textile. It’s a piece of Americana,” said John Doerner, Chief Historian at the Little Bighorn Battlefield National Monument in southeastern Montana. “I hope it ends up with a collector that can share that with the American public.” During the June 25, 1876, battle, Custer and more than 200 of his men were cut d