Larkspur is famous for not staying true to its original color (which is why it can be hard to find good seed, most often it is sold as a mix). In my yard I notice it most with petunias. Sometime in mid summer seedlings from last years crop show up and by fall they are blooming and none of them are ever the color I planted last year.

I think that in most cases the original color of the wild form is the dominant color and all other colors would be recessive - But - color is a combination of many genes and different types of plants handle color differently so there is no easy answer as to whether pink is recessive.

yep- i've too seen the color change of plants in my yard. like John, it always seems to run towards the native specie's color, whatever that is for the plant, which makes sense. I've had the same color change you had with both torenia and larkspur, plus cosmos, pansies, violas and nigella have all switched around.