Huh? Yes, that happened to me after installing Ubuntu 14.04 - in my case it was Italian! I don't know how that came out, but I remember that during install, the keyboard layout was initially set to Italy, and sometimes other GEOIP stuff seems to set Italy for nearest mirror servers...
Anyway, here's how to change the language of the clock/ calendar indicator widget:
Go to System Settings > Languages > Regional formats (tab2)
and set display of numbers, dates, etc. to your language.
Click: Apply system wide.