Am I mistaken that NOS means parts that were made in the era but never used?...
No but the "in the era" part is perhaps a bit ambiguous.
NOS, New Old Stock, means it is a part that was made long enough ago to have completely through the normal flow of manufacturing/distribution channels without ever being used/installed. It now has reentered the distribution process and is being sold under the guise of NOS to additionally denote that while new, it has sat around for some time and any warranty extended the part when new is not likely to now be applicable. Also, the seller's own inventory is what is available through that channel. If a replacement due to defect is desired, the replacement may very well not be there if the purchaser "got the last one".
A key point here in my understanding of NOS is that NOS applies to aftermarket parts as readily as it does OEM parts and it applies to parts that were made well after other parts for the same vehicle that are NOS. IE, NOS can apply to a made-in-1972-for-Honda wheel and it could also apply to a made-in-1982-for-the-aftermarket wheel. Both could be NOS. Of the two, only the former would be OEM NOS. I have purchased far more NOS labeled parts from the latter category than the former in dealing with '50s era cars and trucks.
The key difference here between my interpretation and others' above is that I read the "Stock" not as meaning OEM but as meaning "inventory", as in "Yes, I have that in stock". Thus NOS is not held as meaning OEM as it is commonly applied to aftermarket parts.
I went off to ebay for an example and funny thing is, the last item I had viewed is an example. Item number: 350118085368. This is an auction for some Redwing shocks, NOS is in the title. These obviously are not OEM. Likewise, item number: 370224212922. Here the seller quite clearly states OEM and Genuine Honda vs just using NOS.
After all this long windedness, I say you received an NOS wheel if it is new and was manufactured 10+ years ago.
Ken