Nothing wrong. Cold blooded creatures only need to get their bodies tempreture up to the level required. Once target achieve, no need too much sun, in fact, have to avoid the sun to prevent it from being toasted.
So early morning is where the sun is impt to them to get their tempreture up and get active. Noon is the time to avoid the sun and rest. Evening and early night are better times to be active and hunt. As the night gets later, they probably lose body heat and have to retire to bed.