Toadstool has yellow patch

Hi everyone, I have had my brown toadstool in the tank for over a week. When I got it from the LFS there seemed to be a small section along part of the edge that looked damaged like a small chunk was missing from it. It has a neon yellowish color and the coloration seems to extend along part of the edges near the damage. Is it going to be alright? The rest of the coral and even spots that are yellow have very good extension and appears healthy, I just don't want it to be something that I shouldve treated but didnt and lose the whole coral. Could the damage perhaps be something munching on it at night or anything like that? I don't know if toadstools have predators or not, but when I got it I did see a white Asterina in the bag with it while it was floating and when I went to remove it the star was gone, presumably hiding in the rock on the base of the Toadstool. Would it be causing this damage?