Should shiro miso have a slightly moldy smell?

Hi Maki--I love reading your blogs and I've learned a lot about Japanese food on my visits. My question concerns some shiro miso I just bought. It's the first time I've used it (previously using red miso) and when I opened the container, I noticed it had a slightly sweet, almost moldy smell to it. I just used a few teaspoons to make a cup of miso soup with some wakame (yum!) and it tastes fine. Is this smell normal? I never noticed this smell with the red miso. It's a fresh variety called Miso Master, available at Whole Foods here in the Boston, MA (USA) area. What do you think? Thanks and keep on cooking/blogging! :)