I have noticed that when currys or chillies are frozen to eat later, they 'mature' and become noticeably hotter.  Can anyone expain this?

I'm aware of how it's done for dairy products and that, it being rather easy to tell when it's going bad. But I was just preparing some Charlotte Potatoes and I noticed it said "Display Until July 8th. Best Before July 10th". It's now October 22nd, but I wouldn't surprised to see them still good at 3 months given how they looked and felt.

They were stored in the veg drawer of a fridge that is at 2C +/- 1C, but even when we have gotten big bags and kept them in the garage they've kept for several weeks, though they did start sprouting (some were even got to by Field Mice before anything else).

So, just how did they come up with such a poor date for "Store in a cool, dry place"?

Sometimes it also appears to exhibit pitting (with no visible insects to be found -- though it's unclear, with all the packaging, if some of the pits were developed during manufacturing) and a slightly rancid (?) taste. White chocolate of similar age seems to be less affected. Caramel centers in chocolate seem to dry out with time, leaving a dry residue.

Chocolate can melt in one's hand, but slight cooling can also make it hard enough to damage some dental work. What accounts for such change?