I had trouble not laughing out loud when he made the original comment. The possibilities are

1-- He has the same understanding now as he did then, but understands what happens physically with his track better than its effects on the time of races.

2-- He knows more about it now.

3-- During the conversation (and in this article) he indicated people always accuse him of changing the track. It's possible he felt he had to defend himself to me about making changes himself, rather than them ocurring naturally, as he says here they do, and wanted to maintain that nothing was changing.

My guess is 3.