We have noticed that the state of the Bitcoin network currently requires transaction fees substantially higher than 100 satoshis per kb in order to get confirmed within the first couple of blocks. We have increased the fee to target 200 satoshis per kb in order to ensure quick withdrawals. If you deposit, please make sure to make sure to have the transaction include a sufficient fee!

https://bitcoinfees.21.co/ is a handy tool to see what fee you should use.