You’re right of course, now that it’s been established the name appeared in the 1961-62 Polk, the earliest her name could have been included - going by the ‘she started at the U of WA in September’ - was in the last three months of 1961. As the directory is a useful marketing tool, under those circumstances, the book couldn’t have come out before end of the year...and the information it contained would have been already outdated by one year.
I doubt if the people who relied upon the directory would have found that very useful...
But it’s evident isn’t it, that Anna Obama was in Seattle early enough to be included in the directory and furthermore, early enough to be able to enroll at the university.
The discovery of Anna 0bama in Seattle really threw a monkey wrench in their works.