I like the way this both covers the time gap and invites change by bringing in the new quaestor prime. I like Lucullus' character so far, as well. I'm not so sure about that title, though. I would recommend introducing a new rank title instead. In our normal police forces, you would have a Detective reporting to a Sergeant reporting to a Lieutenant, and so forth. Distinctions by class (Private 3rd Class, Private 2nd Class, and so forth) usually break up categories of people on a relative parity. Lucullus is portrayed as a senior officer, not as an elite peer.
Not much more to say here, it's a good springboard to bring new chapters to the story.