It's because ETH network, not intended delay. They are doing pretty good though!
Already more than 94,451,872.40 USD raised!
Not intended obviously. There were errors along the way and then there were ETH blockchain cloggings recently. And then just hours before the final closing of the ICO, there was a server error that was fixed immediately. There is no big deal with this extension. After all this is not an indefinite or even a week-long extension. Here's the announcement they released:
ICO runs until Ethereum blockchain block 4917092 is reached!!
Approximately Tuesday 4am GMT
Overall, the ICO is extended at few days. What will happen to the unsold tokens? When it's burn or not created, does it be that the max number of tokens will be reduced? Or the tokens will be sold afterwards in the exchange?