I just upgraded to Gantry 4.1.13 on Joomla 2.5.14 and the latest version of Panacea template. Maybe it fixed one mobile template bug, but it introduced another one. As soon as I upgraded, people couldn't get to my site from their phones AT ALL. I ended up re-installing Gantry 4.1.12. Don't you do any regression testing before you issue a new release?
Did you clear Joomla and Gantry cache after the update? Did you try to check in your server error logs to see if you will find some php error messages? What was happening to those people when they tried to access the site?
we are aware of mobile issues caused by the latest gantry upgrade.
we're currently working on several template and gantry fixes which should be ready for release beginning of next week.