Paul, that is an interesting moral question that you raise.
Personally I see no problem in raising a query about something you used to own, even if it has been returned to the seller. And anyway, there are plenty of queries about sales items by board members, and some folk may not even have an intention of buying.
However, if I were in the same situation, and a confirmed ID was given here, I would then pass all the info to the seller, or send them a link to the message. I might even mention to them that I had raised the query here in the first place.