I did notice that the owner of a large mining pool was receiving error notifications from Mt. Gox. This mining pool has tampered with mined blocks to include religious messages, so they'd definitely be in a position to do transaction malleability attacks to provide Gox with plausible deniability.

/r/bitcoin thread with sources: http://www.reddit.com/r/Bitcoin/comments/1zifxf/why_is_the_a...