This post from an exit node operator to the tor-talk mailing list a couple of days later seems to bear out these suspicions: https://lists.torproject.org/pipermail/tor-talk/2014-December/036067.html
It now appears to be less bad then originally feared:
https://lists.torproject.org/pipermail/tor-talk/2014-December/036078.html
The likelihood of this being the work of law enforcement seems to be lower than originally anticipated.
This post from an exit node operator to the tor-talk mailing list a couple of days later seems to bear out these suspicions: https://lists.torproject.org/pipermail/tor-talk/2014-December/036067.html
It now appears to be less bad then originally feared:
https://lists.torproject.org/pipermail/tor-talk/2014-December/036078.html