Humidity dropped again for no reason??

The humidity has been 99% for a week or so and suddenly dropped to 94% again today for no known reason (it's with press-n-seal and I never even opened the incubator since then), and I see further dimpling in my eggs now. I still see the water level in the perlite. I literally have no idea why the humidity has dropped again. Does anyone have any clue?

(changed the thread title because I still have questions...)

Sealed egg bin and humidity still drops slightly? I've never had that happen. Just a guess: You might be seeing relative humidity drawn out of the air (in the form of condensation-'rain') in the egg bin due to varying temperatures between the interior/exterior of the bin vs. the heat source.

Note: A few percentage points low of humidity isn't going to be enough to dimple/ruin your eggs. You may be witnessing a different issue.