I find it quite unbelievable that this is an actual quote from buffet... With any basic knowledge of statistics you know that 125 isn't ordinary intelligence ...
It's about 5% of the population, so not normal in the sense that most people have an iq of 125, but normal in the sense that meeting someone with an iq of 125 is not terribly uncommon.
I suppose he meant that an IQ of 125 corresponds to the sort of intelligence that is not especially hard to find (and is thus "ordinary"), although it is still above average and higher than the score of most people.