Actually, the issue wasn’t her Age, it was her length of Residency in the United States before his Birth.
IF Obama was born outside of the Country, and his Mother did not meet the prior Residency requirements of five years, which she didn’t, he would not be considered an American Citizen at Birth. I assume upon his Mother’s return to the United State he would have been Naturalized.
Because he was Born on U.S. Soil to an American Citizen, the prior five year Residency of his Mother was not an issue.
That is why his Country of Birth was an issue, especially since he was toted as being Born in Kenya in one or two College Year Book Bios lauding his wonderfulness.
Obama, Jindal, Rubio, and Cruz are ALL ineligible to be president.