They wouldn't of added it to the market and announced adding it on twitter if it wasn't ready. I guess there's thousands of deposits/withdrawals going on and it takes time to process them.
This "delay" happens too when they put up mint,dark and cach earlier, they said "Trade engine for these markets are offline until the morning to allow our wallets/security to catch up and prevent many deposit issues that arise soon after coins are listed"
https://bitcointalk.org/index.php?topic=481015.20