We've seen a lot of unconfirmed transactions on bitcoin sent to us today, and I've just had a report from one customer that the bitcoin we sent him hadn't confirmed yet. My best guess at the moment is that the rise in price of Bitcoin Cash may have caused miners to switch to it temporarily due to the extra profit they can make and this caused a sudden increase in the fees needed to get fast confirms on Bitcoin.
As you can see in link below, fees for fastest confirmations have gone up: https://bitcoinfees.earn.com/
