My opinion: a dicrefenfe in political traditions.Putin expected that Bush will call Saakasvili and the Saakasvili will call back his troops immediately. Bush believed that Georgia must decide itself - as he did not act way too long during Katrine because he believe in state sovereignty and that it was a competency of Louisiana. Saakasvili believed that he got at least a nod and wink from US. Actually, he could get encouragement - of course not from State Department, but may be from a friend at Cheney staff, or McCain stuff, or may be a member of Congress... His culture is very receptive to hints.