Sally raises an important question. If you are misting with hard water, then the minerals in the water are collecting on the leaves. If the white residue was there when you got it, then it probably pesticidal residue from greenhouse overhead spraying.
It's harmless but should wipe away with soapy water and a little elbow grease. There are also commercial leaf cleaning products that rinse away mineral deposits very easily and leave a shiny finish. One such product is called BrandX.