What In-Joke?

In one episode, Sex and the City (SATC, for those who seem to be in the know or who like unpronounceable acronyms) gave Carrie Bradshaw's address as:

245 East 73rd St.
(whose zip code is 10021)

Simply a fiction?

Does this belong to anyone who might be in a position to sue on the grounds of 'invasion of privacy'?

Tortious, that is to say?

Or: does this belong to one of the writers or producers and makes for a great teasing self-glorification?