A friend of mine downloaded the character and the patch and just had his badass rank reset. This particular glitch isn't exactly new, but it seems the new patch and/or DLC might be another trigger for it. After investigating the official forums it would seem he got off lucky. People are reporting losing not just badass ranks, but skins, heads, golden keys, and even their actual character saves. There are also reports of character saves getting corrupted.
No word on how widespread this issue is but I just thought I should get this info out there for anyone playing the game.