[devilsdata]

It does not. I'm Australian and our timezones are ahead of the US (NSW time is about 15-17 hours ahead of US Eastern time). If I took a flight from Sydney to New York (22~ hours) on my birthday, the US custom's officer would wish me happy birthday when I landed the next day.

Therefore, birthdays are not bound by timezone at all.

[throwaway290]

it's a cool thing to wish happy birthday on the hour they were born (if you know it) but I can't say the same about preparing for deadline.

I don't get a happy birthday from customs though, cool!