I would have called them. 100%.

As a business owner, I’d want someone to tell me I’m screwing up. The actual risk (of primers igniting and causing a problem) is low, but the liability associated with making that kind of mistake and being penalized by the law is, I would guess, high. God save you if there was a real problem in shipping and someone got hurt.

I care more about the person/business than I do about saving $25 on my order. Call it Karma or The Golden Rule or whatever you want, it’s my experience that doing the right thing is always the right thing.