At least i have not own the 309 long enough to witness such a change.
As for the availability of brushed or polished Ti, if i am not mistaken, while there is no completely polished Ti Lumes, there is a few or one that has a combi of brushed and polished Ti, polished being on the bezel.
But i'm not that much of a luminor guy, so the others would have to help you in this!
Cheers
Stephen