It's the same message for me as well now "Sorry we are down...", and this morning I played a few rounds of Farkle without any problems. I guess it's hard to be calm about this, especially if someone has some balance on the site, but I hope everything will be alright.
I don't think it's something serious, Betnomi is around for a long time, they probably have some problems and I guess we will see them online when they fix it.
In such situation that they are genuinely down for the sake of maintenance, they should be able to make official statement so that their restive customers will be assured they are coming back after such maintenance. Moreover such unannounced maintenance really look worrisome or they had some glitch. I can imagine what is going on in the minds of those having huge balance and large withdrawal to make.