You don't think banks and exchange offices charge fees? Of course they do, a posted rate could be .8 and getting the currency at the bank would get you only .75 just as an example.
Hopefully its only temporary but who knows, and I'd imagine they can't do instant exchange on there side which is why the fee considering there would still be exchanges going on in their site even when the market is closed and they could suffer a big hit if the market opens down the next day from when it closed the previous.
That is my thoughts on it anyhow, not that I'm happy about any fees or anything and unlike most sites at least you can deposit in your own currency and not get dinged huge fees that way and previously no fee to exchange that currency to US funds which you'd play in. On 888
for example I lose over 10% between deposit and withdrawal if not more, if I deposit say 600 US and then withdraw 600 US I wind up losing about 100CAD because of the "fee" they have on currency exchange but its not indicated as a fee its simply that doing a deposit I probably get .75 and then on a withdraw I only get .7 (obv I don't recall exact details but looked at it a couple of times, and that's why I don't even contemplate depositing on there these days)