Sounds to me like they were trying it on, as plenty do. If there really was an issue, you would have heard back.

I'm sending a refund to a buyer later tonight. They don't know it yet. When I was packaging up their items today, I noticed that in the description of one of them, I hadn't updated vital parts when I used the sell similar option to list it. It's 100% my fault, so will send them a refund for that item. I made more than enough profit on the other 4 items they bought so I won't be out of pocket.

I checked this buyers feedback after they'd bought (they were a last second biddder). Lots of negs left for sellers and lots of positives for refunds. Some were just mentioning that the seller had refunded excess postage that they'd paid, others were for NAD's where they had been refunded. The negs were all for unresponsive sellers. I'm hoping that by refunding before they get it will be enough. They've bought countless different things and all the things they've bought similar to my items all got good positives, so am crossing everything!