it depends on what you call normal? it is really difficult to figure out what is going on in that neural net of theirs.
what is prolly happening is that it has found a spot that it likes. now you have to figure out why it likes that spot. more likely than not it has to do with the current. either this is where the current pushed it so it stayed or the current is flowing in a way that the anemone feels it will have the greates chance to capture food. see if you can replicate that current in a better spot where the anemone can get some light. you might need to suppliment its feeding, if it stays under the rock.
G~