What kjvander said.
I don't know of any reg that doesn't come from the factory nitrox ready.
Regs aren't like tanks.
Tanks, during filling (nitrox.....non banked) HAVE to be O2 cleaned, viton "O" rings and special lube (Christolube, Tribolube, etc.) because they'll be exposed to 100% oxygen at some point.
Your regs, (90% of us) will never be exposed to greater than 40% Oxygen.
So, for what it's worth, regs only need to be serviced as part of the routine maintainence.
It has nothing to do with nitrox rules.