Why did Santorum do so well in the Charlotte suburbs?
Well York County was the home of down-market televangelists Jim & Tammy Bakker, in which they built their religious Disneyland. You are probably too young to remember them. My brother and I visited that particular Disneyland about 3 months after it closed, but alas could not talk our way in for a viewing of its attractions. We commiserated with a nice black lady at the gate about just how sad it all was, that the dream had died.
York County just ain't Romney country. So with him so anemic there, that left a bigger chunk of the anti Romney for Santorum to share as a guess, and some chunk of the anti-Romney are also anti-Newt. Uh, the Bakkers were liberals, at least Tammy. She was known as very gay-affirming and even was during their televangelist period, when gays weren't too accepted even in mainline churches (or secular circles that matter since they were basically at the time serving as an AIDS scapegoat.) Their son now pastors one of those progressive hipster churches I love so much in NYC that has the motto "Grace + Provocation + Love" and campaigned for the gay marriage passage in NY.