I Got A Hole In One Today, Illegally, I Guess.

[ProfessorGAC]

6. Your Playing Partner Is Wrong

First, congrats on the ace! I've more eagles than I can count, but never on a par 3.
There is no such rule making a hole-in-one official or unofficial, merely a recommendation.
You couldn't have walked off the course at that moment, but 9 holes is enough.
From the USGA:

The USGA recommends that a hole in one be considered valid: If made during a round of at least nine holes, except that a hole in one made during a match should be acceptable even if the match ends before the stipulated round is completed.

IOW, 9 holes is enough, and 8 could be enough if one aces the 7th or 8th hole and takes an unbeatable lead in match play. (I'm one up, going to 8. I make an ace, my opponent doesn't. The hole is already over & I'm 2 up with one to play. The whole match is over, now. The ace counts