He might! There is a body of evidence that has not been probed at all, that affects his very citizenship. Under the law that granted him citizenship, he must have a five year continuous US physical presence any time between the ages of 14 and 28. A trip across the border resets that five year clock. Anecdotal evidence has him traveling to the UK and to Canada after the age of 14. I would not assume it is a slam dunk that he ever went a continuous five year period without setting foot outside the US, before he reached the age of 28.
where does you link say it resets?
http://www.freerepublic.com/focus/news/3396601/posts?page=269#269
the following has to do with naturalization process - not citzens at birth, however, the concern over the term ‘continuous physical presence’ doesn’t necessarily mean they must not leave the US during this time:
Physical Presence
Applicants are required to show that they were:
Physically present in the U.S. for thirty months within the five year period before applying, or (see legal basis)
Physically present in the U.S. for eighteen months within the three year period before applying in the case of qualified spouses of U.S. citizens (see legal basis)
continuous presence requirement:
Absences of more than six months but less than one year may disrupt an applicants continuous residence unless the applicant can prove otherwise, (see legal basis, see policy manual)