New at Reef tank, need help on my toadstool coral

Hi I am new to this forum and my name is Zhen. I am worried about the health of my green tip toadstool coral. Along the edges of my toadstool has turned white, I dont know if i should be worried about that. The polyps are all opened, only some parts of the edges are turning white. Please help! Thanks. I posted two pictures below.

Attached Images

	image (1).jpg (67.2 KB)
	image (2).jpg (75.4 KB)