Might be dehidrated, give him plenty of water. Especially if hes out side for long periods of time..
Also give him a spot of shade in his cage, i put a small towel over one corner so he has a place to get away from the sun..
My veiled is pretty passive so i dont see him get angry too often, i wouldnt know if thats what happens when theyr angry..
These are pretty cool if your keeping your guys outside..
Im still working out the kinks on how to filter the water from the hose so they get as little chemicals as possible..