brief but humorous French-language encounter

I was shopping at the SSG Food Market close to my office this evening. When I got to the cheese section to buy some Parmigiano Reggiano, a staffer saw me grab the cheese, and she asked in Korean whether I liked hard cheeses in general. I told her I was making a dish that required Parmigiano, so I wouldn't need any other cheeses. I then asked her where I could find butter that was less expensive than the W22,000 brick of butter sitting on a lower rack, and she guided me around the dairy stand to where the cheap butters were. "Do you prefer salted or unsalted?" she asked. I told her it didn't matter, so she picked up a small brick labeled "Le beurre demi-sel," i.e., half-salted butter, and translated as "slightly salted butter" on the package. I thanked her, but I noticed her reaction when I spoke the words "beurre demi-sel" aloud in French. So I asked her in French whether she spoke French.

"Oui," she said.

And she did not elaborate.

At that moment, I thought better of torturing her by peppering her with questions in French. When someone responds with a simple "Oui" and says nothing more, she's probably hoping not be to quizzed on her French ability. People with actual ability usually rattle on about how they lived in France or in some other French-speaking country, and/or they talk about their education, which may have involved learning French. A curt "Oui" comes off, to me at least, like an "And please ask me nothing further." So I let the matter drop.

I could be wrong about this woman, of course; she might be native-level fluent in French, and perhaps she didn't want to torture me by displaying her overwhelmingly superior mastery of the language. But I doubt that very much.