Hi.
I own the Tudor BB almost 3 years, so far still keeping the good time and power reserve.
I think it is pretty standard , SC will give 2 years more warranty on the work done after the complete service/maintenance. During that period they will cover /repair any fault include the accuracy of your watch. What I heard the in-house movement service can be done only by authorised SC. The proper tool need to use to regulate the movement.