Robinson said it could take a while for a Lotto winner to come forward, depending on the player.
"Some people who win big are really quick to claim, they might check their ticket straightaway, they might know that a prize has been won and know to check their ticket."
"But a lot of people as well have their own routine that they'll stick with when they're checking their tickets.
"They might check their tickets at the same time each week, so they may not check it for a little while."
But she said it was "very rare" the prize was not be claimed at all.
"Normally prizes are claimed pretty quickly after the win, particularly MyLotto as well," she said.
The lucky numbers in Saturday's draw were 24, 1, 35, 22, 8 and 40. The Powerball was 5 and the Bonus Ball was 6.
Saturday's lucky winner is the ninth Powerball winner this year.