Actually Ash stated his position in roughly every region he traveled in. Unova is the only region he hasn't bragged about his past accomplishments.
I remember somewhere in Johto, Ash said how far he made it in the Indigo league, can't remember if it was to impress/brag or if it was just something he randomly said.
In Hoenn he bragged to Max about his placement in the Silver Conference and the Orange Islands, which Max scoffed and rubbed off which irritated Ash.
Sometimes after Ash met Paul's brother, Ash stated his own accomplishments, even when Paul met with Brandon and refused to believe that Brandon lost to Ash during Ash's conquest of the Battle Frontier.
Unova is the only time I haven't seen Ash mention his old accomplishments. He may in the new season with Dawn there cause there was a point in which the two reminisce about Brock and their days traveling together in front of Cilan and Iris.
Actually Ash MAY have "bragged" about his accomplishments to Tripp when they first met, but I can't remember the first two episodes very well.