Can chocolate go off?

[catalyst2]

Just eating some chocolate buttons, survivors of the Battle of the Buttons, I think, but they had a strange consistency, almost gritty. I thought I might look at the expiry date - January 23rd 2003. Hmmmmmmmmm, just a little old. Still, apart from the grittiness, they taste OK. I think I've asked this before but does chocolate really go off?