Why is the fact that the interviewer was half your age relevant? I interview and reject senior engineers with 20+ years of experience every day. They are extremely good at throwing out the right buzzwords and sounding smart, but digging a bit further it's obvious that they have spent the latter part of their career playing politics at large companies rather than doing any real engineering work. A simple FizzBuzz is enough to weed out most such candidates, and if someone refuses to spend 5 minutes of the interview writing actual code (in their language of choice) they are an automatic fail.