http://www.immigration.govt.nz/opsmanual/41527.htm
Qualifications are relevant to employment if:
the major subject area and level of the principal applicant's recognised qualification is directly applicable to the employment; and
the immigration officer is satisfied that the qualification was a key factor in the employer's decision to employ the principal applicant in that position.
I think your qualification is relevant. You are actually qualified for MORE THAN the job you do, and that is quite likely to have weighed with the employer in selecting you.