If she got the original passport in late 1960 or early 1961, she was already pregnant. It was purposeful, not for some youthful adventure or family vacation.
Just because the passport was valid for 5 yrs doesn’t mean she got the first one 5 yrs earlier. Remember that her parents were probably “travelers,” i.e. communists, and they did move four times during their daughter’s childhood. Also, the FBI kept a file on Gramps, but the records were destroyed in 1997. This was no ordinary family.