Kenya tree coral dropping arms ?????

[draco]

I have a kenya tree coral it is about 4" high fully extended we have reciently moved it into a 90 gal tank from our 55 gal . we have had it about 3 months this is the best its ever looked it is full extended but it has droped 2 tips of its arms and is ready to drop a third .And when it drops a arm it is grown over where the arm has droped. it is not near anyting else. all we have is exzena, toad stool leather,and some zoos.as for fish all we have is 2 clowns lol .all of our nitrite,nitrate,Ph,calicum,amonia,alkilinity,salin ity are all good.is this normal ?????