From /r/darknetmarkets (so grain of salt is needed):

> yeah it was about 6-9 months before it shut down if I remember correctly, it was pretty highly upvoted and a lot of chatter about it on the SR forums. though I think there were at least a few bugs that they had to shut down for once they realized that their asses were on the line.

http://www.reddit.com/r/DarkNetMarkets/comments/2flnlp/fbi_s...

So yeah, apparently this was an actual bug.