I do find that from personal experience that when I dehydrate hot peppers the hot peppers do increase in heat and get hotter.
I'm not sure why the hot peppers get hotter when it gets dehydrated but they do at least for me and maybe it's because they release or increase the amount of capsaicinoids that the hot peppers have.
Fresh peppers are less hot to me than dehydrated peppers are but I do love to eat dehydrated peppers and sometimes the extra heat from them is better in some foods.
Sometimes I like eating peppers that are hotter in some things like chili or soups etc especially when I have a cold and need to open up my sinuses.