It will be updated, he could remain there, move up considerably, or fall considerably. Recruiting analysts don't really focus on rankings until their senior year when they see the majority of all the players.
What happened most likely is someone saw Brett play AAU when they were watching some upper tier AAU teams and he stood out enough to warrant a ranking.
Either way I'm sure he's a very solid player, and with still a year left of high school will only get better.