I never gave it another thought until later in the race, when I saw the same dude, although now he wasn't weaving - or running for that matter - but rather, executing a rather slow and painful 'death march' up the first Newton hill or what's better know as Heartbreak Hill. I must say, that there was nothing "natural" about his stride... now. I smiled to myself and continued RUNNING up Heartbreak. I never saw the Five Fingers after that.
Did I happen to mention that I finished the marathon with a Boston PR (3:34), this being my forth Boston in 8 years. Running every step in my new favorite shoe the Nike Lunaracer!