I had that happen too today...
I fixed it by going to the profile page, and deleting what was in the date format box under preferences and hitting save/submit. It then will go back to the default setting.
It should say:
D M d, Y g:i a
or something close to this. Make sure you re-select the right time zone as well. GMT = Greenich Mean Time (main time zone in England for those who are too drunk to fish...)
Okay, so ten out of ten for style, but minus several million for good thinking, yeah?