Wandering BTA disappeared

[trilinearmipmap]

I got my BTA 2 days ago, he seemed in good condition, about 3" size. He settled in to a spot on the rocks, he fed on some mysis yesterday.

This morning I can not find him anywhere in the tank. He must be hiding deep within the rocks. There is no tank crash and the skimmer is not going crazy so I don't think he is dead or shredded.

I expected him to wander but I thought he would go to the more light/high flow areas, not hiding under the rocks.

Tanks specs are:

120 gallon
Mag 12 return
Tunze stream 6060 on with the lights, off at night
8 x 54 Watt T5 lighting -- used by many for SPS so ought to be enough light for a BTA I imagine
Water parameters: pH around 8.25, temp varies 80 to 81 degrees, ammonia, nitrites and nitrates all undetectable

Only tank inhabitants are 2 small ocellaris clowns who ignored the anemone, some hitchiker crabs I have been fishing out, some bristleworms and various other coral frags.

I'm not too worried but I'm wondering if there is anything else I should do.