Just to make it clear, the OP isn't asking where the Aimpoints are made but rather if certain models of Aimpoints have their country of origin on it. If I pick up an EOTech, the bottom has a sticker that says Made in the USA. The OP is asking whether certain models of the aimpoint has the stamp Made in Sweden or if it's something they just do randomly. It sounds to me like ML3 doesn't have the Made in Sweden stamp on it, but maybe other models might.
Hopefully that'll clear things up for you. Honestly this is probably a question you should ask the company directly. Nobody, except maybe a rep from the company, can really say anything about this. Manufacturers probably change things rapidly without notifying the public on a regular basis. A good example is like a candy bar label. It seems like while most might have similar logos, they all appear to have slightly different markings here and there. I guess the problem is it depends on where it is assembled and by what year. Sometimes they might get a new machine that does something slightly different than what the others did.