Presumably the MtGox connection failed and they were using their own bid/ask walls. BAD idea!
Bitfinex is always going to have problems when the volume picks up, because of MtGox. Every darn time price starts to fall and volume increases MtGox always fails, every single time. Every site getting data from Gox, using Gox itself, the live chart take 30 minutes to load and even all API calls are useless. As long as the Bitcoin community and all the satellite sites (Bitfinex) use MtGox, they will fail every single time. This happens a lot.
Bitfinex has some volume issues, but MtGox really causes a lot of problems, order lag there is insane.
/rant
For that matter the MPOE bot had to stop quoting three times yesterday because it couldn't get a coherent feed to base pricing on.
It's a problem.