They should be. They probably get enough sustenance from food particles drifting about and may forage after lights out. Try to resist overfeeding in an attempt to bring them out tho. If you are still unsure try discretely dropping cichlid pellets in their territory while the other tankmates (if any) are feeding.
The main indicator is do they look healthy? Leleupi quickly lose their brilliant colouration if they're are feeling under the weather. Sounds like they're just being exceptionally good parents.