Probably because the wine was claimed by her capital (bottom left) as a fourth ring tile. Therefore Nongomas tiles do not have a "own" connection to the forested hill tiles behind that wine tile.
At least I think this is how it works. It's rare to happen and actually matter, but when it does it's without a doubt weird (especially since for natural border expansion the wine tile counts as 'connecting' and thus natural border expansion should eventually give you access to those tiles).