It's just a hypothesis at this point, a way of explaining what I observed. I might be way off. And with only one hatch as a sample, even my observations might not be representative of what's normal.
Some of the eggs are wiggling a bit. We may have chicks in the morning.
@Alaskan, I don't doubt that humidity affects weight loss. What I'm hypothesizing is that there's a plateau. If humidity is lower, you'll reach that plateau more quickly. Higher humidity and it will take longer.
I don't mean that weight loss will abruptly stop at that point, but that it slows...