Levada's last Mass

The article from The San Francisco Chronicle takes a look at the last Mass of William Levada before his move to Rome later this month. It takes the obligatory look at the sex abuse issue and those who think he's not done enough. It's a standard article. Read it for yourselves if you wish.

I'll just call attention to the last paragraph and the sentence that I've bolded:

Levada's new appointment in Rome will last five years. His successor in San Francisco will likely be chosen within the next six months, a topic of great interest for local Catholics.

Is the AP writer misinformed, did Benedict suddenly introduce term limits or did Levada say he's only going to stick around for five years? What did I miss?