I just had the massage therapist out, and she noticed a bit of hollowing on his back where the saddle sits. I got the saddle fitted just over a month ago, and I use a gel pad to help with any possible pressure. I am a bit confused as to what is causing this hollowing. Could it be because of a bad seat on my part? Could this be caused by uneven muscle toning or an after math of certain riding exercises? Should I be buying a thicker pad to go under the saddle? Does anybody have any other ideas of the causes and/or solutions to this hollowing?