The question of the loss of colors by the 7th Cavalry at Little Big Horn has generated considerable debate. Although this office has no conclusive evidence one way or the other, it has been suggested that Custer's personal flag along with several troop guidons were taken, but that the regimental flag was not captured. A regimental flag subsequently turned up at the Custer Battlefield National Monument in Crow Agency, Montana, but it has never been verified that this was the flag at Little Big Horn. There is also a rumor that the 7th Cavalry lost its colors in Korea. (This had something to do with the 27th cavalry, and the 7th was associated with them somehow).
I don't know if they ever actually lost their regimental colors, though. Seems it could go either way.
Tha above was from an official army site, for what that's worth...