Why is the knight "not gaily dressed"?

The Knight gets one of the more complemetary descriptions from Chauser. The knight, Chaucer tells us, "possessed/Fine horses, but he was not gaily dressed" Indeed, the knight is dressed in a common shirt which is stained "where his armor had left mark" . That is, the knight is "just home from service" and is in such a hurry to go on his pilgrimage that he has not even paused before beginning it to change his clothes. Yes, the Knight was so late for his trip, he didn't get to change his clothes!