The Firefox Firefox 13.0.1 version that you currently run is no longer supported with security updates
You can see an internally generated X-Firefox-Spdy header (e.g. X-Firefox-Spdy:3) in the Response Headers that you can inspect (click the main HTML file) in the Web Console to indicate that SPDY is being used and which version.
THanks for the information. However I do not intend to go to the latest version 16 of Mozilla because they removed the multi coloured certificate notification. this allowed HTTPS to be seen green and other s blue, grey etc.. Until they bring that back I will not update. Also Mozilla may want to note that Opera uses multicolor certificate information.