I see that you use the W3 Total Cache plugin. This plugin may be caching a desktop version of your site, and then serving it to your mobile readers.
To avoid such issues, I would suggest that you disable W3 Total Cache for mobile user agents, as explained here:
http://www.ninthlink.com/2012/06/29/disable-w3-total-cache-for-mobile-user-agents/
Let me know if it helps.
