I kinda panicked when I checked the older threads about signs of mbd and it mentioned a "flat spot" at the back of a domed shell is a sign of mbd. Keep him outdoors in the hot, humid climate of Abu Dhabi, UAE where humidity remains at constant 80%-90% RH and temps range from 30s to 50s C
If he's eating a decent diet and getting daily sunshine then MBD won't be an issue. However, he does have some mild pyramiding starting. This is typical of hatchlings who spend hours hours a day outside. If your relative humidity is that high, this shouldn't happen, but perhaps the sun is still drying him out? I just know that they don't tend to do this indoors. Shell spraying and keeping the enclosure wetter might help, as long as its not getting too cold at night.
Personally, I don't like to have them outside all day when they are that small. I only sun hatchlings for an hour or so. I don't leave them outside all day until they are around 5-6".