You have to think about it this way: about 90% of the pie is MCAT and GPA; the remaining 10% is for personal statement, activities, honors/awards, and everything else. Furthermore, MCAT and GPA are kisses of death, whereas everything else, including PBK, helps somewhat but don't turn the adcom members head over heels because of it. Every little bit helps.
<personal anectode> When I asked my advisor if I should mention it in my application he said, "Of course." When I asked him if I should mention that I got inducted junior year he said, "Of course!"</personal anecdote>
But I echo the other posters suggestions about mentioning it especially because your interviewer asked you about it.