Probably just getting used to the tank. Seems pretty typical. Most if not all of the fish I have ever added to any tank have always seemed to hide/stick to one area for a couple weeks. It took almost a month or so for my blacktailed gobies to come out from underneath the rocks. Now their pretty illuminscent baby-blue color is seen almost all day as they hover in the current.
I just recently added two false perculas last Sunday. Just last night they made their way towards an anemone that was added on Wednesday.
Typically percula's prefer pairs and a host anemone. But this is just preference and not a rule. Like I said, I'm sure he's just getting used to the tank.
, that's a fine looking fish.