Interesting. I did not know secession sentiment was this strong as early as 1856.
South Carolina appears to have the most virulent form of pro-Secession activists. They have had this streak in one form or another for a generation. Take a look at the Nullification Crisis of 1832:
http://www.ushistory.org/us/24c.asp
Also, when the Abolitionist Movement was just getting started in the 1830s, and various publications were sending Abolitionist pamphlets by mail into the South, the most violent reactions came from South Carolina.
http://history1800s.about.com/od/abolitionmovement/fl/Abolitionist-Pamphlet-Campaign.htm
The agitation expressed in 1856 was nothing new. George Templeton Strong’s vexation with South Carolina was probably a common political feeling in the North by now, and Northerners are already thinking that South Carolina is the cause of all this controversy. It will be easy to transfer a sense of vexation into anger once blood begins to flow in the Civil War. And in about eight and a half years from now, after over three years of war, that anger is going to be vented on South Carolina with a vengeance.