Does it taste like cloves with a little bit of tartness? WLP530 is what you want for Leffe Blonde.
I've never has a belgian wit that tasted sour ... are you confident in using that term to describe the taste? Sour to me is biting into a lemon - never had that from a beer, nor would I want to.
No, I think you're right it's tartness I reckon I'm tasting.