If thgis is the new growth coming in a lighter color, this is not a problem, just the nature of the plant. If the existing foliage is going a whitish silvery cast, acloser look might show it to be the scars of lots of small sucking injuries, a sure sign of mites (one of the reasons to keep plants outdoors as much as posible; the dry conditions in our homes are tailor made for mites).
As usual our best recommendation is neem oil; it is a great miticide as well as a pesticide (no, they are not usually interchangeable) and a fungicide to boot. Make sure to spray to sturation getting under the foliage as well. Wait two weeks and repeat (to get the next generation).
Seems a likely culprit, but without images I am flying blind (literally!). An image would be really helpful for better diagnosis...