That is not considered calibration already. That is call "repair", which means their lens have a much more serious problem than just front/back focusing, a major problem, in fact.
If you think your lens is soft, and has a problem, then send it in. But you have to be sure it is a problem, not just a problem with your technique. And when I say soft, it means it is really really soft. Not you-think-it-is-sharp-but-you-want-it-sharper. If you bring it in, and the service technician, or customer service staff ask you what is wrong with your lens, you need to be able to tell them what is the problem. If you tell them you want it to be sharper, they will attempt to calibrate the AF accuracy first. And if you already have spot on focus, that extra calibration might just throw it off a bit.
Why don't you post a pic where you think it shows that your lens is soft. There are a lot of experts here view your pic and tell you if you need to bring your lens in or not.
And the "calibration" in your 7D, just allows you to tune your AF to adjust for back or front focusing, nothing more.