Yes it’s hard to imagine Romney not winning enough states if wins by more than eyelash nationally.
There have been close calls (see 1916) but Tilden is the only guy to win the popular vote by more than 1% and not get the most electoral votes. And his popular vote margin was illegitimate cause many Blacks in the reconstructed Southern states were not allowed to vote Republican.
In 2008, Obama won the national popular vote by 7.26% (52.87% for Obama and 45.60% for McCain) and got 365 EVs. Had McCain increased, and Obama decreased, their respective vote percentages by 4.47% in every state and the District of Columbia, McCain would have won the national popular vote by 1.67% (50.07% to 48.40%) but Obama would have still defeated him in the Electoral College by 278-260. And had McCain increased, and Obama decreased, their respective vote percentages by 4.76% in every state and the District of Columbia, McCain would have won the national popular vote by 2.25% (50.36% to 48.11%) but there would have been a 269-all tie in the Electoral College and the Democrat House would have decided the election.
But the 2008 elections were an aberration in more ways than one, and I don’t think there has been a presidential election in which the “fulcrum” state (the one that would need to flip in order for the other candidate to win assuming that such candidate gained votes by an equal percentage in every state) was one that the winning candidate carried by such a high percentage above his national victory margin. If Romney beats Obama in the national popular vote by 1%, I think he’ll carry NC, VA, FL, OH and NH and get to 270.