Ok, fair enough. But this seems like a colloquial meaning of 'should' to me. There's no question that an English speaker would say it that way, but another way of saying it is "I probably have some"
It's always interesting when a word has multiple disparate meanings in one language. If you then have a single word in another language that is taken to be a translation of that word, does it have the same spectrum of meaning, and if so, is there something deeper underlying it, or is it possibly a borrowing, or just a coincidence?