Mattress tufting is not symmetrical

Hi, I am very happy with the two mattresses which I have just purchased, my question concerns the tufting. The 1st line of tufts start approx. 12 inches from the end of the mattress where the label is sewn on, whereas at the other end the line of tufts start approx. 6 inches from that end of the mattress, i.e. they are not symmetrical. This is just an observation, as I am very pleased with my purchase, and would recommend your mattresses to all my friends. Many thanks.