Yes, it's fine. There is no such thing as 100% NaOH with zero impurities. NaOH always has some impurities due to its ability to very quickly react with water and carbon dioxide in the air. Water and sodium carbonate are the main impurities found in NaOH. As you use the NaOH, these impurities will increase every time you open the container and allow room air to enter.
For those reading this, please do not confuse impurities with additives --
Don's NaOH is 100% NaOH in the sense that no one has intentionally added something else to the NaOH to turn it into another kind of product. As I've just explained, NaOH naturally contains some % of impurities. But no one has deliberately added, for example, aluminum particles and colorant to turn it into a drain cleaner.
Another example -- the water you drink is 100% water, but it naturally contains impurities that normally are dissolved in water that comes from wells or lakes and rivers. If you add sugar and flavoring to that water, you no longer have 100% water. You have a sweetened drink.
