So: Is it the Andy Rooney Effect, or is "So" So Big of a Deal?

You may, or may not have noticed the uptick in "so" as a sentence starter, [There actually hasn't been an uptick, but there has been an uptick in noticing it]. Or, so says Geoffery Nunberg, resident linguist on radio show, "Fresh Air", on National Public Radio [USA]. 

I have noticed that I use "so" as a sentence starter to indicate that I'm about to talk out loud on something that I have actually been talking about to myself, as though I'm bringing a new interlocutor into an ongoing conversation. There's probably a more elegant way to do that. So, I'll have to think about it. Or maybe, I'm using it the way Nunberg suggests, as a preface to a lengthy verbal outpouring.  So, "So..." may be a way of turning off my ears...thus, therefore, so - I should pay attention. To "so".