It is not the issue from that exchange but it is the time taken by the miners for confirmation and those transactions are confirmed sooner which have high fees while with lowest fees you will need to wait for sometime.
Hi i do understand that concept it is just that the fee seemed high enough. Reason seemed to be big backlog of transactions on network
http://statoshi.info/dashboard/db/transactions reason for this spike is unknown to me (DDOS?).
Anyway transaction cleared overnight.