I'm not sure if it's 100% true of most pickups, but it seems reasonable. I'm assuming his numbers are center to center for the poles. If your strings are about 2" apart (center to center), that's only .125" less. Cut that in half, and that means that the center of the string would be .0625" from the center of the pole piece (with everything aligned nice and straight).

That difference is very, very small. I would guess that much of the string will be over much of the pole, plus all of it is probably sitting easily within the effective magnetic field. Once it starts vibrating, it really moves in and out over the pole. Besides, even with a string perfecly aligned over the pole pieces, you don't notice a drop in volume when you bend a note.
"To crush your enemies, to see them driven before you, and hear the lamentation of their women." - The Governator