I also use WP Supercache and WPTouch. After doing an upgrade to WP Supercache, I'm having the same problem you are, I think. First, my readers reported getting a big black dot over the comment area when they tried to leave a comment. Now, I am getting the mobile version sometimes and the desktop version other times.
I thought I had fixed the problem when I went to Advanced Settings on WP SuperCache and updated the Mod Rewrite, but the "fix" didn't last. I'm not a tech person so I'm struggling here. Has anyone else responded to your query?