Heya, Steve!

My first thought was magma upwelling... sure, you live pretty far east of where the stuff bubbles up from the subduction zone to form the Cascades, but Yellowstone is pretty far east of there, too (hotspot, perhaps?). But then you said the epicenter was only a couple of miles deep. If there haven't been any hot spriings or geysers show up recently, I guess the magma theory is out. ;-) Especially if the geologists are swarming the place - meaning they don't have a ready explanation from pre-existing data.

Since you asked... the Appalachian orogenesis was sooooo long ago that most of the faults have settled down completely. I lived in a more active zone in the Philly suburbs than I do now. There are a couple of faults to the west and north of there which wiggle every year or three, in the 2+ range. The cat I shared my digs with at the time got in trouble for knocking a potted plant off a windowsill... I had some major apologizing to do when I learned I'd slept through a 2.3!

As they used to say at the end of roll call on Hill Street Blues: Be careful out there...

E'