What physical sensations in your own body usually signal that you are in the presence of a covert narcissist?

On extending a late birthday wish, why do many people say, "Happy Belated birthday, …," instead of , "Belated Happy birthday?" After all, the birthday was not late but occurred right on schedule; it is the greeting that was offered late.
How can you deal with anxiety before a first date, especially if you have a history of difficult relationships?