Length of Vertical Scar After TT
The scar that was made around your old belly button was round. When it is closed it from side to side it forms little peaks (do ears) at each end that must be trimmed off to make the scar flat. This makes the resulting scar longer. The "hole" was in the middle of that vertical scar. That's how far down it moved, but when your surgeon trimmed it the scar extended up toward (and it your case to) your new belly button. It also extended down an equal distance. This can't be helped. It's the same reason that the more vertical height of the tissue that is removed from your abdomen, the longer the lower scar has to be if the ends are to be smooth and not have bulges at the ends.
Tummy Tuck vertical scar
When a tummy tuck is performed, the abominal skin and fatty layer is loosened, pulled down, and the appropriate amount of excess tissue is removed such that the incision can be properly closed. When that is done, the old belly button hole is moved down, and often times it is moved down far enough that it is removed. if it is not removed, then that hole is closed in vertical fashion giving a scar running up and down. In a situation like you describe, the old belly button hole was only moved down a short distance, and thus the scar is sitting right below the new belly button hole. I typically recommend that my patients use a scar cream such as Biocorneum starting 2 weeks after their surgery. Check with your surgeon before using that though.
Tummy tuck scar
Clearly this is a question that can most appropriately answered by your treating
surgeon.While there you can ask for their recommended scar fading advice.