It seems some players are receiving some paid store items to their accounts without even noticing it! And some are pretty awesome too.
We’ve actually seen this type of thing before, but it’s still unclear whether it’s a bug or an intnded soer of giveaway, as Blizzard have never commented on it. In this particular case, we have limyg0113 wondering how they got a pretty great mount from a store bundle, when they definitely didn’t buy it nor collect it from a free offer. The mount in question is the Nether Lion in its base state. It’s one part of four in a bundle worth 2100 Platinum, with the other being mount accessories.
But this isn’t an isolated case either, as other players report getting pieces of the bundle as well. Some got the mount armor, some the mount itself. This isn’t the only bundle this has happened with either, as players report getting Barbarian transmog without ever having picked it up. There are actual free cosmetics giveaways, both with free items for everyone and random specific store ones becoming free. However, those always need to be claimed by players directly and it’s pretty clear when you do.
One theory goes that this is the same model as the current Bast Reliquary mount, Ferrukal, Thrall of Iron, and that perhaps the game added both. However, we don’t know whether any of the players who reported getting the Nether Lion actually unlocked the Beast Reliquary.

So it does seem this one’s a bug. So go on over to the store and check out if you got some freebies!