Thorsteinn, who is mad on Lego, wanted more mini-figures for his collection.
He took $14 out of his piggybank, got a subsidy from his mother and went to Farmers where they were on special.
The figures come in loose packets with opaque packaging. He said sometimes you could tell what was inside by squeezing them.
"I squeezed four and figured out what they were. "Then I got sick of squeezing and threw them all back in there and picked out eight."
He started opening the packages on the way home in the car.
He got a Roman warrior and two Amazon warriors and was planning to give some to his 2-year-old brother Kristin.
He was just opening the last packet as they crossed Dublin St Bridge, and that's when he found Mr Gold.
He was so excited his mum Annie Kristinsson had to stop the car and take photos of him with it, to post on Facebook.
Thorsteinn may have the 19th Mr Gold to show up in New Zealand. Worldwide 1676 of the 5000 have turned up so far, an internet source says.
He's a savvy youngster, and thinks he will be keeping his.
"If I'm going to sell him I will wait until he's worth heaps, maybe a deposit on a house."
Thorsteinn has been playing with the plastic construction toy since he was about 5, and has many boxes of Lego in his room.
His first set made a plane. Since then he's had helicopters and pirate ships, and lots of Star Wars and Ninja pieces.
He's made a Lego movie using the school camera, and he especially likes to build war scenarios. That's what he had lined up at home when he talked to the Chronicle.
"I made a city and I've got heaps of troops armed to take it," he said.
