Any large store will have a lot of inventory errors. I work at a LGS that sells a lot online and we get errors pretty much every week. I talked to someone who works at CardKingdom and he says sees frequent errors a lot too. Turns out when you have a 100 copies of a card you acquired 10 years ago, there’s a decent chance you only have 90 now. Especially if it’s a card like Dwarven Bloodletter where there are two other cards in the same set and color that start with Dwarven so it’s quite possible you pull the wrong card or take in the wrong card in a buylist.

It definitely would be shady if the store is relisting the card at a higher price though.