[OCDP]

Overfeeding wont so much put your RBTA into hiding, but will increase the chances of a split. If you happen to be feeding too much, this could be why he's hiding (split)

I have had many of mine split as well.

I suppose you could ask yourself the most basic questions ...

Have you added/changed anything in your tank?
Are you overfeeding the anemone?
Water paramaters (which I am sure are good..)
What kind of light/flow was it in? Too much flow? Too much light? Or not enough, etc, etc.....
Clowns stressing the anemone?

FWIW, RBTA's tend to wander a lot more than the basic tan colored BTA's ... I am sure it will come out of hiding soon.

If overfeeding isn't the case.. how often/much do you feed it? Might just need a chunk of food !