him showing black could be either. you do have to watch the temps. even if you put his cage partial to the shade for him to retreat. dont rely on this.
i have a yemen that insist on basking no matter of the temps. it was close to 100 today. his cage is available to the sun only in the morning and evening. when i got home it was still very hot outside. it was about 5 and even with partial shade. he was out in the sun showing hot colors and gaping. so i blocked more of his cage and even with that effort he still went to the 1/4 of cage being in the sun.
how they live in the wild i have no clue. we must pamper to much in captivity they lose there wild intuitiveness.