We should not be too surprised to see the surveys narrow as the Scottish Referendum approaches. This tends to happen as the ambivalent folks leaning towards Yes start saying yes rather than undecided. Mobilization is occurring. More importantly, this study shows that the range of outcomes includes a Yes victory.
The biggest threat for the No movement, other than the British government doing something really stupid (like threatening to pull out of the EU some more), is complacency. Turnout matters. And that is really where the uncertainty is. Between now and September 18th, people may not change their minds much about whether Scotland should be independent or not, but they may change their mind on whether they will vote or not.
I am no turn-out expert, but I think this news story, if it gets played up in Scotland, might be good for the No side. While it might encourage more Yes people to vote, complacency is the big threat for the No side--I don't have to vote because the referendum will fail. Well, now they might just be a bit less confident and a bit more mobilized as well.
So, perhaps the folks at Monkey Cage are doing the No side a favor?