Thanks, Radical618 - though tragically I don't think their secret will last.
I must say that I was rather impressed that although yes, we the audience guessed throughout the year that there seemed to be something going on, despite repeated prefaces of "I know they can't be together, but..." that for the most part, they did spend the year incognitio. Which, for two private work-a-holics may not be THAT unusual, but it does say that the commitment both to the job and the relationship were handled respectful - yes, in terms of the characters, but also in terms of the writers.
It gives me hope that next season isn't going to be like "screw everything you know about these characters' personalities - it's a free-for-all now"