Why did the skin of my tomatoes fracture after a few days in a refrigerator? I purchased a bunch of red tomatoes on a twig a few days ago, and put them in a plastic bag in my refrigerator.

When I opened the plastic bag five–six days later, all the bottoms of the tomatoes (bottom tertiles) had wide fractures in their skin. They had basically started to split.

They were a bit soft, but not that soft – my first rection was that maybe my fridge is a bit too cool.

The temperature in the fridge is around 5-6° C, and I kept the tomatoes close to the bottom shelf where vegetables go.

Is my refrigerator too cold, or was five-six days in a fridge too long to store tomatoes?

Note: I'm partially aware of the fact that tomatoes shouldn't really be stored in a fridge – but in room temperature – if I'm not mistaken!
Tomato Gardening Tips
This site's gardening tip says that tomatoes splitting on the vine is due to a lack of water - the plant gets dried out and the skin doesn't retain the elasticity to contain new growth. 

The refrigerator is typically a dehydrating environment. Could be that's your culprit.

But for pity's sake, store them on the counter where they stay their most delicious and you can see them and remember to eat them!