My cat does this too. She also makes the same noise when I do dishes (metal utensils clanking) and I'm pretty sure it's because she doesn't like either noise. I know sometimes cats will interpret sneezes to be a "hiss", but it all depends on your sneeze. It's very obvious that my cat just hates the sound of my sneeze, probably because it's usually loud and abrupt, because she cries and gives me a terrible look like I'm totally annoying her.