Use "December" instead of "Dec". "December" is more user friendly. Why you need to short it?
Edit: My ayes look for full names. I've never used the short ones. (And I'm trilingual)
The box is not large enough to fit all the full name months:
See the very basic example here :
In fact it could work on some sites like gaming:
But not meta:
Also I don't really see the point of having full names printed. Anyone can understand it with a little. In the same way, we should write the year in full format: 2010? I'll stick to the K.I.S.S. paradigm.
Having the full month perhaps marginally improves the readability. For that, you get a broken layout - not very ideal.