certainly before they get Secret Service protection at taxpayer expense and before they are sworn in, but preferably before they go on any primary ballot. Senators and representatives too.
Age and being a "natural born" citizen are the only two Constitutional requirements for POTUS. The birth certificate shows both. And Senators and Reps have an age requirement and a citizenship requirement for a certain number of years (though they can be "naturalized" citizens).
I don't like any provision of the Constitution's being completely disregarded.
There has been controversy over a significant number of POTUS candidates, including, ironically, George Romney. Wiki has a list.
http://en.wikipedia.org/wiki/Natural-born-citizen_clause I realize that the Obama-Kenya insanity was about Obama's being black, period. (I think Obama may have been trying to protect his mom, who was a very young and apparently unwed mother involved with a married man when she gave birth to him--and he hinted about that when he said publicly that Bristol Palin's behavior was not a legitimate basis for political comment, citing his own mother.)
The racism and insanity in this cases doesn't mean, though, that, going forward, we should not be more mindful of the few Constitutional requirements for POTUS, Senator and Rep.