I got it from fleabay. It was more than likely bent when it was stacked during shipping on that particular side and the weight of the board bore down on that slot. As I mentioned in the OP, the RAM was left in the slots, so any weight bearing down on it, the RAM stick would act like a lever, regardless of how well packed it was. There's no other damage or problems beyond that single slot.
I stripped the sticks out and got the "no memory" beep code of 5 shorts and 1 long. Stuck a stick back in the bent slot and powered the board up and it works. So that's good news. I was worried that it had separated somewhat from the board and would cause a short when powered on.
I've sent a message to the seller with the pictures and a recommendation of not shipping boards with RAM still installed. If the board had failed to boot, I'd return it. But as it's booting I'll keep it.