I tend towards the assumption that there's nothing major behind announcement delays. That is, there's nothing for us to worry over/get excited about. It's probably just making sure that everything is in place promotion-wise before hitting the Go button.
But it's the "newly mastered" bit that worries me. There's absolutely nothing wrong with the mastering on the first three albums - in fact, it's pretty much as good as one could want IMO. Together Alone could use a little less compression but my expectation is that we'll get more.
Whatever it is, it'll be what it'll be... I just want to see some track listings!