Everything sounds fine tank wise...and I concur with MT79 that with 125g of water, you can rest easy at night that you won't wake up to disaster if it does pass. After a bad batch of salt (and a large water change), I had one "melting" before my eyes that I kept in the tank for over a day before I was sure that it was dying and removed it. This was in a 55g. Just keep a watchful eye, you will have little doubt if things are really going south.
In the meantime, I would completely leave it alone. They really don't require feeding in the presence of good lighting, although you can feed meaty foods to supplement their diets. I would not use phytoplankton in the future, but rather small chopped up pieces of fresh, uncooked seafood (shrimp, fish, etc.). Keep in mind also that feeding your fish will inadvertantly feed your anemone at the same time, I am down to feeding my BTA pair once every two weeks or so, and will probably elimate it altogether. I found no real benefit from the heavy feeding I started with.
A picture would still be nice to get a good look at it, if possible.