Difference between using -san and -shi

Question

I was at an event with high ranking Japanese personal, heads of a martial arts organisation. People were asking for signatures on event passes, which had their name written on it. As part of the signature, one gentleman was writing the participants name:

ジョーさん

On the pass.

On mine however, he wrote:

ジョー 氏

I have read about the formality of using 氏, as used when you do not know or have never met the person, however we have met many times, both training together and meals, parties etc. I have great respect for him, and he knows me by name, so I was wondering if there is anything else about the use of 氏 in this case I can learn.

Answer 1

There is no such rule that "氏 is used when you have never met the person". Where did you learn such a rule?

氏 does look relatively more formal, dignified or respectful, but at the same time, less friendly. Still, さん and 氏 are both natural options here. If you are getting an autograph from a young adorable idol, さん would be more usual. However, it is not unnatural at all if a great person in the field of martial arts used 氏 on his autograph. From what I can see, I doubt there is a special implication here.

Answer 2

I find it weird that he used 氏 there, not because it sounds excessively formal or business-like but because it is not a form of address to be used for a second person directly (if not as a joke).