Definitely a fatal flaw in that respect. Buyer will end up with bad experience, and seller with bad reputation 😕 That's the last thing I want when growing a business.

It could also be a client side issue if the payment goes through, the mint processes it, but either the client is closed/inactive before the token was processed or there were rate limits on verifying the token with the mint. The latter was an issue happening on the site a few days ago which has now been resolved, but even if it were still persisting, there was error handling in place to make sure you changed your mint before ever trying to make the purchase.