In my opinion, the BTA will go were ever it seems content on the lighting, flow, ect. It may just be acclimating it's self to your lighting and hiding out a bit and if it needs more/ less light I'm sure it would move/ down up your rock work to get it. Good Luck!
P.S. You haven't said what your lighting is but I'm guessing if the anemone isn't immediately at the top; grasping for light then that you probably have strong enough lighting. Also, I believe they are a medium to high light anemone.