So, the line that separates the signature from the post:
Code:<div id="ctl00_Main_forum_ctl01_MessageList_ctl06_DisplayPost1_ctl24" class="yafsignature">
This seems to show the separation header for the signature only on YAF Pro for me. I did an upgrade from 1.9.1, and tried removing all theme files and replacing them with 1.9.1. Then, I replaced all 1.9.1 with 1.9.3 files. I also tried deleting all files and only uploading 1.9.3 theme files.
I'm not sure what to try next... maybe I just need to look at the CSS and give it a shot.
Regards.