Russian Tortoise Q

Hi guys! Last year, my fiancee and I rescued a russian tortoise from the LPS - well, they rescued it, we bought it, etc. Anyway, we've been keeping it healthy and happy, according to some of the good tortoise experts out there. However, when he came to us, he had some large yellow bands on his shell in between the pleurals and marginals. These look very thick and out of symmetry to me. Is this abnormal, or no? The LPS said that they rescued it from a keeper who was not feeding the tort properly, so it may be a case of poor nutrition. What do you think?

Here are some pics.