Well that's interesting. I don't know, could be me overgeneralizing from my own experience. At least where I grew up, "calm down" was never used charitably. It was always designed to be annoying oneupmanship. It was as if getting too excited wasn't cool, because it meant you weren't "mature enough" to be jaded, and that sort of thing.

(I've found it extremely difficult to shed associations from my time growing up, and despite years on the Internet, communicating with people all over the world, my dominant associations are often still just based on the culture I was exposed to during those formative years.)