There were 12 entries in the weekend's championships which were shorn on "stroppy, big lambs", weighing about 60kg, and Humtsad qualified in third place for the final, and was sixth in the international competition heats, which had 24 entries.
She withdrew from the international semi-final to concentrate on her big Norway team opportunity, although doubting her chances right to the moment the result was announced.
The lambs in the final were good shearing, comprising 10 Norwegian White lambs (crossbreds) and two Spelsau lambs she described as "madness on 4 legs."
"I started with some good lambs and kept up with the boys for the first couple of sheep," she said. "Then I had some trouble with a kicker and fell behind."
The commentator kept talking about the boys "and which one of them would go to France," leaving her sure she was "out of the game."
All three others beat her by more than two minutes, a 57-second second-to-last sheep and the best quality points enabled her to sneak home by 0.34pts from runner-up Lars Sonstevoldhaugen.
"I actually won," she said. "Can't believe it."
"Working in Dannevirke and Masterton, and also competing, have been very important for my development," said Humstad, "getting numbers of consistent sheep have been good practice, and also many great shearers to learn from. It is one of the main reasons I've come so far in such a short time."
"Doing many competitions in New Zealand has given me enough experience to know what the judges are looking for, to stay calm on stage and do a good job."
Humstad plans to be back in New Zealand soon, with some other Norwegian shearers, although she's unsure when.
One of the few other women to win a national open title, possibly the only other, was New Zealand shearer Michelle Harrex, who won the South African open final in 1998.