Those that felt it, report it here:
http://earthquake.usgs.gov/earthquakes/dyfi/
JR:
Early scuttlebutt is it occured along the Spotsville fault, which if memory from my time mapping in Western VA is right is ~400 MA, but is more related to Mesozoic activity (~200MA) (MA = Million years ago). I don't remember if it is a fault related to the opening of the Atlantic and the break up of Pangea or not.