As the attempt to suss out the meaning of the Massachusetts Senate election continues, Alec MacGillis weighs in today with a typically interesting piece in The Washington Post. The article’s headline, “Brown’s victory in Mass. Senate race hardly a repudiation of health reform,” is a little misleading, though. MacGillis’s thesis is actually that health care may have been key—but not in the way that you think:

While many are describing the election to fill the late Edward M. Kennedy’s Senate seat as a referendum on national health-care reform, the Republican candidate rode to victory on a message more nuanced than flat-out resistance to universal health coverage: Massachusetts residents, he said, already had insurance and should not have to pay for it elsewhere.

Scott Brown, the Republican state senator who won a stunning upset in Tuesday’s election, voted for the state’s health-care legislation, which was signed by then-Gov. Mitt Romney (R) and has covered all but 3 percent of Massachusetts residents. That legislation became the basic model for national health-care legislation. Brown has not disavowed his support for the state’s law, which retains majority backing in Massachusetts.

Instead, he argued on the campaign trail that Massachusetts had taken care of its own uninsured, and it would not be in the state’s interest to contribute to an effort to cover the uninsured nationwide.

Brown, in fact, has been quite explicit in making this argument. As MacGillis writes:

“We have insurance here in Massachusetts,” [Brown] said in a campaign debate. “I’m not going to be subsidizing for the next three, five years, pick a number, subsidizing what other states have failed to do.”

In a news conference Wednesday, he said, “There are some very good things in the national plan that’s being proposed, but if you look at — and really almost in a parochial manner — we need to look out for Massachusetts first… . The thing I’m hearing all throughout the state is, ‘What about us?’ “

Of course, just because Brown made this argument, and voters supported Brown, does not mean voters supported Brown because he made this argument. As MacGillis notes, “Divining voters’ motivation is difficult,” and it’s made more difficult in this case by the absence of data.

But there are signs that this may become the smart liberal pundit’s explanation of choice for the election, and the broader political moment. At his blog, Matthew Yglesias had a post up this morning that didn’t mention MacGillis’s piece, but did embrace its premise: “And now the voters of Massachusetts have thrown a major wrench into the works by electing a Senator who says not that health care should be left up to the tender mercies of the free market, but rather that since Massachusetts already has a universal health care system he doesn’t care about anyone else.” He refers to this as “Health Care’s ‘I’ve Got Mine’ Problem.” (In a subsequent post Yglesias flagged, and praised, the MacGillis article.)

Greg Marx is a CJR staff writer. Follow him on Twitter @gregamarx.