blue throat trigger strange behaviour

[Gregs]

recently introduced a blue throat trigger to my display tank about a week ago. first day quite shy, second day he was out and about and eating. this went on for a few days. now ive noticed day 6,7,8 hes been missing. found him wedged in a cave, so i thought maybe he was stuck. i removed all the rock and then he just swam out and into another cave and wedged himself into there. his color is fine, breathing ok, no noticable wounds or diseases, not sure what the problem might be?
anyone else noticed this sort of behaviour with the blue throat trigger?
Other fish are fine in the tank. parimeters are good.