This is one of those situations only humans can establish. Have you ever been contempted by an acquaintance (not a friend, but someone you just know by sight instead) for not telling him/her your birthday? Ok. More details are needed:

Imagine a car. 4 people on it. We are going to a Japanese restaurant. Eduardo is driving. It Rains. Lisa, his girlfriend is in the co-pilot seat. David and Anya in the backsits. The episode starts:

Eduardo: ah, by the way, happy birthday again David.
David: oh, thanks.
Anya: what???? She suddenly stares at David with a perplexed face.- What??? Is your birthday??? And you didn’t tell me?
David- Pues no..
Anya: Why????
David- I don’t know…now you know…
Anya: Ohh….SooOOOooo disapointing…You didn’t tell me. You are stupid, and particularly surprising coming from a PhD…You could have had a party, I would have organize it!!
After that, David’s sci-fi reply would have been: Get off of the f*** car, you b****!! But the Austin Power’s gentleman was in charge that night and smirking, David replied:

-I am a man of mystery, I suppose….

Anya is from Kamchatka, aka: a far east region only 0.00001% of earth’s population can point out in a world map. David just met her literaly twice. O sea, he knows her barely since 1 month ago.
Yeah, next time David will have to do hire a public relation firms to avoid another Kamchatka situation