Sure, a few polls had Sanders beating Clinton by 20 points, but they were among his best polling outcomes. Likewise, on the other side of it, a few polls had him beating Clinton by only single digits. I thought for sure urban areas of the state (which helped Clinton out so much in 2008) would do so again now. Probably not enough to get her a win like in 2008 but at least some.
The only thing I can figure is 1. Sanders really did have a significant home state advantage being from Vermont, 2.) New Hampshire Dems have become more liberal the past eight years, or 3.) a combination of those.