Vietnamese names can be a little strange. In college, I had a professor whose first name was usually given to women. All of my Vietnamese friends thought the prof was a woman when they first heard the name.
I know the feeling. My name is Simone and I am from Italy. In most of the world, they think it's a female name (usual guess: French lady) until they see me :)
This sounds much like the famous "Boy named Sue" song.