A bug with the payment for that one village?  Like I said, I've defended many NPC villages.  I am always accepted withing an hour or less and I always ask for 1g (just hoping to get paid something).  Never had this problem before.
It ended up accepting me just before the battle, although I had applied 10 hours or more before it was to start.  It all worked out in the end, we defenders put up a pretty good fight too.
There was probably some minor issue with the server or something, I just hope things like that can be minimized.  It's hard enough to get people to defend those villages without having to deal with bugs like this.