First-name basis, huh? Cool! [he's usually inclined to call thirties-and-up adults by their last names.] So I shouldn't be shy then, huh? All right.

Possibilities. My friend's memories were of a human man who traveled with an elf. He probably learned it to relate to them better. That could be the case with your guy, too.

Or, he is an elf. My friend described the one he saw as human-sized and graceful. Could be worse. Apparently they have a liking for poetry, I know part of this epic ballad he pulsed back.

There's also the idea that the other you picked it up through study or was taught by non-elves, and the language was more of a curiosity or to have a language most people don't understand. Like for me. If nothing else it's good for taming animals and talking about things most people won't get.