Because it was his first ace, he was also unsure of the protocol once reaching the 19th.
"I'm not sure (about shouting drinks), I'll have to wait and see."
The good form continued for Henrickson. He shot a gross 83 for a nett 69, or three under his handicap.
The ace comes hard on the heels of club member Kevin Edmonds' hole-in-one on the 13th on Sunday.
Castlecliff manager and golf pro Rodney Donaldson said he was unaware if aces had been scored in the senior tournament before, but predicted Henrickson would be odds-on favourite to take the nearest the pin prize.
"We have a nearest the pin prize on all of the par 3s and I'm picking this guy will win that," Donaldson said yesterday.
The tournament had attracted 138 golfers including 96 men and 42 women from throughout the country.
The field includes Andrew Markman from Mt Maunganui who has won three of the last four senior championships, while defending women's champion Ann Braithwaite from Stratford was a red hot favourite to reclaim her title from last season.
Markman was not that happy with his first nine, but came home well to card 75 for a nett 68, while Braithwaite was pleased with her first day performance carding a gross 74 for a nett score of 68.
The tournament runs until Friday.