Given example, why did the dirctional derivative change from <1,2> to <2,1>?

EX: What is the directional derivative in the direction <1,2> of the function z=f(x,y)=4x^2+y^2 at the point x=1 and y=1. The gradient is <8x,2y>, which is <8,2> at the point x=1 and y=1. The direction u is <2,1>. Converting this to a unit vector, we have <2,1>/sqrt(5).