I came to America as a small child, speaking only Spanish. My parents were both fluent in Spanish (my mother was Mexican), but they spoke English in America and I quit speaking Spanish at some point. I lost the language and can no longer speak Spanish, but I still have a memory of it. When I was in Pecos, Texas, recently a lady in a restaurant commented that I was having a conversation in English with the Mexican lady serving the food. She found it curious that I could understand the serving lady speaking in Spanish and I could answer her in English, which the serving lady understood.
It was nice of the lady passing by to point out how the serving lady and I could communicate even though I did not speak Spanish and she did not speak English. I did not really think our encounter was unusual, but maybe it was.