Translation of the GNU GPL copyright notice

The copyright notice of software released under the GNU GPL (as of v3) contains the following sentences:

You should have received a copy of the GNU General Public License
along with this program. If not, see https://www.gnu.org/licenses/.

I found some programs in Trisquel (Gawk and Caja for instance) show translated notices instead, based on my locale settings.
OK, good. But I suspect there were mistakes when the volunteers translated it to my native language, so I would like to discuss the meaning of the modal verb 'should' in the first sentence.

I reckon there are a dozen meanings of the word 'should' and maybe the most frequent uses are
- presumption
- assertion
- obligation
- blame (when used with 'have + past perfect')

I think the right meaning of 'should' here is the first case, i.e. something like 'You probably have received a copy of ...' or 'We presume that you have received a copy of ...'. However, the translators seem to have understood it as the third example (or maybe the fourth!). Maybe I could be wrong, as I'm not a native speaker of English either. However, translating every 'should' to the third example above (and thus mixing it up with 'must') is a very common mistake in my language, which is the reason I am suspicious. Also, it's the distributors' obligation to include a copy of the license, not the users'. ;)

Such (possibly incorrect) translation appears both in the GNU awk git repository and the Ubuntu language-pack package, so I'm not sure where it first originated from. If my guess is right, I'll maybe suggest them a correction of the translation, or not :)