You know from your nitrox class that the US diving industry reached a consensus several years ago that most scuba equipment does not have to have special treatment as long as you are using enriched air with an oxygen concentration below 40%. (Check your owner’s manual to get the details for your particular gear.) This is not the case in Europe, and even in the US does not necessarily apply to your tank and valve.
In your class you learned about proper labeling of your tank, but you should also be aware that your tank and valve may require special cleaning in order to be properly prepared to be filled with enriched air. This is because one of the common methods of making enriched air is to introduce pure oxygen in to your tank, then topping it up with air to obtain the requested O2 percentage. Since the tank and valve are exposed to pure oxygen during the filling process, they can represent a hazard to the fill station and the blender if they are not adequately cleaned and compatible with oxygen.
The cleaning process removes any combustible materials that may have accumulated as a result of filling and using your tank, such as compressor oil, metal oxide particles, dirt, and debris from wear of o-rings and gaskets. These materials could act as kindling, and result in a catastrophic incident during the filling process. So be kind to your fill station operators and nitrox blenders, and have your enriched air tank oxygen cleaned when you have your annual visual inspection done.