I agree with every one on this subject. There is a large amount of reasons he could be uncomfortable with the subject. I'm leaning towards the hasn't been done in 14 years one myself. Something new like that might make him uncomfortable because it's never happened before. I'm also sure if you continue to approach the subject he will become more comfortable talking about it, and you both will reap the rewards.
Have you flat out asked him if he was uncomfortable with the subject yet? Sometimes the straight forward approach works as well.