How very interesting. The Snow Peak web site advertises the Litemax stove thus:
Our lightest and most powerful backpacking stove, the Litemax is made from ultralight, durable Titanium and anodized aluminum for hikers who need to cut ounces without sacrificing boil time.
No steel is mentioned.
However, comparing the image of your stove with the images on the SP web site, we see some curious contradictions. The current SP Litemax burner has slots, while yours has rows of holes. Not the same stove! But not so fast either. Two possibly older photos on the SP web site do show rows of holes in the burner head, while the rest of the photos show slots.
So let us look at the GigaPower stove GS-100. The curent model is made from steel and aluminium, but both my GigaPower stoves are GST-100 models from some time ago, and they are titanium and aluminium. The models have evolved over time.
So I suspect your Litemax is an early model built with steel and aluminium, before they switched (upgraded) to titanium and aluminium. In which case … that may well be rust after all.
My recommendation would be to clean the rust off the best you can and then to always keep the stove dry. The current amount of rust looks to be pretty harmless. I often carry such small stoves in little proofed nylon stuff sacks – the BRS-3000 comes with one, as does the FMS-300.
Cheers