It might depend on what Customs or Immigration talked to you about and what you told them. If they asked you whether you were intending to look for a job while in New Zealand and you said that the purpose of your visit was to take in the beauty of the Bay of Islands, but somehow ended up with a job offer, then they might well take a dim view of this. If on the other hand, they just talked to you about how clean your hiking boots were, then there is nothing to worry about.
There are other points to keep in mind, such as a minimum income your job has to earn, your qualifications, if your skills are on the shortage list, etc.