If the moisture content of the part is too high, it can expand during soldering and damage the part. The larger the part, and more humid the climate, the greater the risk. Iron, toaster oven, and frying pan all expose the parts to rapid temperature gradients.
If you're concerned, the parts can be baked (maybe about 80c) for several hours before soldering them.
If the new bags are moisture sealed and you pack the desiccants along with the parts, there should be no problem.