I've been coding professionally for about 12 years now, coming to the profession relatively late (age 27). For the first 4 or 5 years I suffered from 'the smartest guy in the room syndrome' and probably believed I was a _master_. Then I got into _Agile/XP_ and realised that I was nothing special and there were lots of much smarter people out there that I should learn from.
Currently I'm unable to say what craftsmanship means to me without sounding corny; I may edit later. Craftsmanship stems from deeply caring about your work and having the humility to realise that you may not be currently doing the best possible job.