Maybe something like the Lavabit scenario where they rather close the shop than sell their users out. On the other hand, proposing Bitlocker as an alternative would be rather suspect in that case.
I'm not going to jump the gun just yet but after snowden it's not out of the question.
edit: Confirmed Microsoft stores your recovery key on their servers if you're not connected to a domain: http://windows.microsoft.com/en-AU/windows-8/bitlocker-recov...
Whether or not they superstitiously store it anyway is a different question.
I suppose they could be approached by someone to plant backdoor into the software, but I wonder if that can be done without someone noticing it...
EDIT: I normaly don't care. But this time I'd be glad if who downmoded this post explained why.