The WPPSI-III is okay for this year in NZ and AUS, as the new WPPSI-IV with AUS/NZ norms just came out in 2014. But, yes, the scores are probably slightly inflated. The Flynn effect is generally considered to add about 3 pts to the FSIQ for each 10 years distance from the standardization group (the WPPSI-III NZ norms came out in 2004). So that might drop her FSIQ to the 99.7%ile, not a meaningful decrease in the real world. (That would be from the mid 140's, which is 99.9%ile, to the low 140's, which is 99.7%ile.)
Can't explain why the psych would make her change her grip during testing! Leave that to the OTs.
I think your test results would suggest HG, even with a minor adjustment for norm obsolescence, especially considering that the FSIQ is a low estimate, based on the PSQ being a very low estimate.
It is possible that a very sensible, socially-aware four year old may have figured out how to blend in better with her age-peers, thus making herself appear less gifted than she actually is.
