Start with the enclosure
Check the basics for Ceratogyrus marshalli: fresh water, suitable moisture, a secure retreat, good ventilation and a practical temperature range of 21–27°C. A clear husbandry problem matters more than a single evening of unusual activity.
For Straight Horned Baboons, keep the enclosure mostly dry, with upper substrate with some lower moisture and clean water. If the enclosure is obviously too wet, too dry or difficult for the spider to use normally, correct that issue before looking for a more complicated explanation.
Know what is normal
For Ceratogyrus marshalli, Straight Horned Baboons are fossorial tarantulas, so normal retreat use should make sense for that lifestyle. A hidden spider is not automatically a stressed spider, and a visible one is not automatically comfortable.
With Ceratogyrus marshalli, changes from the individual's usual routine are more informative than a generic list of 'stress signs'. Compare activity, feeding and retreat use with what the same spider normally does.
Climbing, pacing and restlessness
If a Straight Horned Baboon repeatedly climbs or paces, check enclosure shape, moisture and recent disturbance. Mature males of Ceratogyrus marshalli may also roam much more after the ultimate moult.
One short burst of activity from Ceratogyrus marshalli matters less than a persistent pattern combined with poor body condition or an obvious enclosure problem.
Feeding changes
With Ceratogyrus marshalli, food refusal in Straight Horned Baboons is often normal around premoult, after a heavy meal or following a rehouse. Keep water available and remove ignored live prey.
If Ceratogyrus marshalli stops eating but remains well hydrated and otherwise behaves normally, observation is usually more useful than repeatedly opening the enclosure and offering food.
Changes that need quicker attention
In Ceratogyrus marshalli, visible injury, haemolymph loss, severe dehydration, inability to stand normally or major loss of coordination in a Straight Horned Baboon deserves prompt attention.
If Ceratogyrus marshalli is physically deteriorating, correct any obvious husbandry problem immediately and seek experienced or veterinary help where appropriate.