Don't worry, it's not mold!
The white particles you are seeing occur because of a phenomenon called cocoa bloom. When cocoa reaches a temperate of 75° F or above, the cocoa changes from solid to liquid and will rise to the surface of the nut butter. After this bloom, the cocoa butter reaches the top of the jar; as they're exposed to cooler air temperature, crystals begin to form. These crystals are white and can be smaller or larger depending on the temperature the product was exposed to.
Please note that while it can be mistaken for mold, we assure you that it is not! Consuming nut butter when these crystals have formed will not harm you and should not change the taste of our products!
Although we do our best to keep our products at a cool temperature, once it leaves our manufacturing facility, it is hard to have complete control over the handling of the product.