While reading this answer, I noticed some odd wording in Article II, Section 1 of the Constitution (emphasis mine):
No person except a natural born citizen, or a citizen of the United States, at the time of the adoption of this Constitution, shall be eligible to the office of President; neither shall any person be eligible to that office who shall not have attained to the age of thirty five years, and been fourteen Years a resident within the United States.
Does this mean that, to be eligible for the office of President, one must have been a citizen when the Constitution was signed or otherwise 'adopted', presumably years ago? If not, what does "at the time of the adoption" mean in this context?