In general, one data point is meaningless, two is worth investigating, and three makes a trend.
That said, I don’t really care, because Cain is a terrible Presidential candidate anyways. 9-9-9 is a huge tax increase and wealth redistribution plan, stealing from the poor and giving to corporations. Cain has no coherent policy on social issues; he had a rational moderate stance on abortion that he flipped on when he realized it wouldn’t fly with Republican primary voters.
By all means, if you want 4 more years of Obama (which I do, for the record), nominate Cain. He has the potential to get thrashed worse than Mondale did. He reminds me a lot of Sharon Angle, the woman largely responsible for Harry Reid holding his senate seat.