I assume you have had your well water tested and it is considered "safe" for you. That test may have also listed certain minerals in it. That's why it would be recommended to not use well water in an incubator. As the "hard" water evaporates it leaves those minerals behind. Depending on what mineral are there and in how strong a concentration you could certainly get a residue that could cause issues in an incubator. You can get the same issues with bottled water or tap water from a city system. It just depends on how hard your water is.
I certainly agree with
@AGeese. I have no idea what is in yours.
I'll admit that I'm not as worried about this type of thing as some other people. If the water is good enough for me it is good enough for my chickens, dogs, and other animals.
Growing up on a farm I saw broody hens hatch eggs and take their chicks to drink from a farm pond that dogs, horses, and cattle also drank from. It had fish, frogs, and turtles living in it. That was the water source for all of the farm animals. There was no way I'd drink it but they all did and thrived.
Now my dogs and chickens get tap water. I dump the water every day to keep it fresh and to keep mosquitoes from breeding and growing in it. When it rains they may find a mud puddle to drink from, both the dog and the chickens seem to prefer the mud puddles.
Personally if it is safe for you I would not worry about it. They may even benefit slightly from any trace minerals in the water. But if you are the least bit concerned, use a different water source that you are happy with. It is your concerns and desires that should be important to you, not mine.