FWIW, magnificas are about the most beautiful anemone out there, but they do tend to wander around a good bit unexpectedly.
They might stay put in the same spot for months, and then suddenly for no apparent reason start wandering, and in the process kill just about everything they crawl over.
If your tank isn't coral-loaded, you should be fine. Keep specimens you are particularly attached to in places you wouldn't expect a magnifica to go to, meaning, the lower reaches of the tank.
You have a stunning anemone that seems to be in good shape. I am in agreement with someone above who said that taking it back would probably kill it, so in your situation I'd be inclined to hang onto it. You seem to know what you are doing and you CARE about taking good care of the anemone. That's a LIGHT YEAR from what a lot of folks do--- which is just throw it in there and see what happens.