When you say the algorithm affects 0.3% of searches on google do you mean you select each query with a probability of 0.003 and pass it through this algo, or this algo is used 100% of the time when query A is followed by query B and these combinations account for 0.3% of all searches. If it is the latter then the fact that Obama is a magic keyword may mean that you are biasing a very high percentage of political searches. I am sure election involving an incumbent is an edge case which is very difficult to account for, but now that we know of this I hope google will try to correct the results to remove these specific accidental biases in the future.