Moving cast iron from fridge to stove

Yes, there's a danger but mostly if you're blasting the dutch oven with a lot of heat. Say from the 'fridge to the hottest burner of a professional stove. I wouldn't worry too much; those things are pretty tough. (I've done this many times in the decade I've cooked with dutch ovens. So far, so good.)

Another reason you likely don't want to do this is because the cycles of reheating (if you reheat more than once) may degrade the flavor.

I cook in cast iron. Chicken, beef, pork, fish, or anything. As long as it cooks through, I throw the whole (cooled/covered) pan in the fridge. Some stuff will taste irony/rusty. You'll know what you do and do not like. If it was cooked it won't poison you. So stop worrying. Throw it back on the stove, heat it up, and eat those delicious leftovers like God intended. Tho an inexperienced cast iron user should be careful as rust can form in the pan and may be a heath risk

I often make soups and stews in my dutch oven. I have, on many occasions, taken the oven directly out of the fridge and back over the fire. While this practice is not recommended, I typically use a low flame to reheat foods in the dutch oven and have never experienced any problems.