I think you're right, I know many of the huts have some area that you can enter and get out of the weather. I found some other details on the NH Fish and Game site:
http://www.wildlife.state.nh.us/Newsroom/News_2007/News_2007_Q1/Search_2_Rescues_011107.htm

Apparently they called 911 at 3:30pm yesterday. They were on a "day hike". If they were on a day hike, and were still above tree line at 3:30pm, they hadn't planned too well. I think sometimes it's hard to come to the realization that you're out of your league, and might need some help. By that time, they should have long since realized they were in trouble. By waiting so long, the SAR team was out in the worst conditions, at night, looking for folks that didn't really know where they were. It sounds like their cell phone eventually died, but, they had a rough location at that point. These folks might have been kinda frosty by morning. The team found them at 1am. Good thing they had a winter sleeping back with them to stay somewhat warm waiting for help.