Y'all being crazy arguing about something have of you didn't even see. He got it called by the line judge because he started with his back foot at the same plane as the center hash line. The call didn't come until he hit the serve, which makes me think it would not have been called if he didn't hit the toss and restarted, but I can't be sure. He was a baby about it, and even said to the ump, why does it matter if I was over the line anyway, which is an argument that the rule shouldn't exist, not his violation of it. Frankly, it ended up seeming to rattle sock more than Isner as sock lost the plot soon after.