I am not sure if the current administrative division of Slovenija is correct in OSM.
Currently it is in OSM that way
admin_level=2 Slovenija
admin_level=3 Vzhodna Slovenija + Zahodna Slovenija
admin_level=5 12 regions
admin_level=8 xy občine
boundary=administrative + admin_level=3 are two statistical regions called NUTS-2 with no administrative functions.
Same with boundary=administrative + admin_level=5, which are NUTS-3 statistical regions with no administrative function.
See http://en.wikipedia.org/wiki/Statistical_regions_of_Slovenia
As far as I know, the government proposal to split the country into some regions was not agreed on in June 2008. So there are no administrave borders between country (admin_level=2) and občine (admin_level=8).
I am no sure if admin_level=3 and 5 should be changed from boundary=administrative to boundary= census, statistic or such?