I think it might be a glitch of some kind. My year finished on September 30th and the website colour went from bronze to blue. I got the email welcoming me as a bronze on October 2nd followed by another today (3rd) telling me I'm blue! Website is still blue.

I am an important passenger for BA as I have 690 lifetime tier points and my last flight was in CE. Just the sort of person they should be cosseting!