Hmm it is the same bag of substrate that I've been using for my ball python.
Perhaps I will switch the thermometer/hygrometer for a different one to see what difference it makes.
I will probably do it tomorrow because I don't want to bother the baby.

The two thermometer/hygrometers in the tub are brand new, and they are the battery type, not analogue.

The water bowl is inbetween where the hot and cool hides are, so it might be due to that. I will move it right into the cold corner to see if that helps.
I just want to know he is safe. Thanks guys