The conventional wisdom was based on the notion that Shea-Porter, being too shrill and leftish, is a weak candidate for that district. Which makes sense but isn't really borne out by 2006-10 results. Adjust for that, and it makes sense that both districts behave roughly identically again (taking into account that Bass is the R's best and perhaps only shot at keeping NH-2.)
Guinta's also proven to be a much weaker incumbent than expected. Shea-Porter has been polling relatively well, so I'm feeling pretty good about NH-1. NH-2 is definitely harder to predict, however, the most recent polling that I've seen showed Kuster pulling ahead a little bit. This small lead, plus Kuster's strength as a candidate, Bass's ethics issues, Obama's likely coattails, and the natural Democratic lean of the district make me think she'll pull off a narrow win.
