I'm just typing this before running to class. This looks funky to me, he just went through a big growth spurt. Could he have smacked his Scute on one of his rocks? I only noticed when I was putting him back in his house after his soak.
It went pinkish when he grew like a crazy thing but it then went back to normal, that new pink spot was enough to worry me, but it's already gone away. Apparently I'm a tad paranoid...
I agree that it looks more like normal growing and not septicemia. Reacting fast or "paranoid" is what can save a tortoise and aid in a quicker recovery