I am at a complete loss as to why that did that to you. I've double checked my files, and the problem you describe isn't on them. I believe that somehow between me printing my own optimus prime and uploading it to thingiverse the file was messed up somehow. Just to be safe, I re-did the joint on the torso completely (deleted the feature, and made a new one identical to it). This should not affect the print at all, it should still work fine. I am re-uploading the .ipt files of both the torso and legs, as well as the assembly. Try re-downloading these files and if the problem persists, I'll look into it further.