One thing to keep in mind about Factory Warranty (I stress Factory Warranty) is the Dealer does Warranty work on a parts and labour cash recovery deal from Nissan.
I.E. what is and isn't covered/voided/constitutes a warrantable fault etc isn't the Dealers call, it is Mr Nissan.
When a potential warrantable problem is noted the Dealer/Workshop/Mechanic has to approach Nissan Aust.
If Nissan deny the warranty claim or want more info then the Dealer has to provide it to Nissan or try and fight the good fight on your behalf.
A good Service Dept. will go the extra yards in the fight, a bad one will just say Nissan said "Sux to be you" and if you don't agree you go duke it out with them.
Bottom line of that is the Warranty support and costs are not "on the Dealer" but are the responsibility of Nissan and the Workshop won't proceed on any work unless either Nissan or the Customer agree to reimburse him.
... for the record I had an EGR block, DP chip, 4Terrain Clutch and exhaust mods on my truck during the warranty period.
Of about a dozen faults I only had two issues rejected, a dump pipe stud issue due to the "aftermarket exhaust" and a Dual Mass Flywheel fault due to the "Aftermarket Clutch"