Yes, that was the explanation I got in history class as well. The flu emerged during World War I, and every combatant country had strict censorship of the press

Yes, that was the explanation I got in history class as well. The flu emerged during World War I, and every combatant country had strict censorship of the press in place, which suppressed news of its spread in those countries. But Spain was neutral in that conflict and thus had an uncensored press, so reports of the flu's impact quickly made it to print there. And those reports got picked up worldwide as the first reporting on the influenza, leading people to think of it as a disease that began in Spain.