Toadstool Leather Question

So, I have had this toadstool leather in my tank for 8 months. Recently, it has started to show this white spot on the center. Does anyone know what it is and if it is a problem.
It looks like this:
 
Any help would be great!

 

I had one do the same thing. I never figured out what it was, and after a couple sheddings it went away. I guessed it to be some sort of irritation, and made sure to run carbon and keep up with w/c. HTH

 

almost looks like some salt creep fell directly on that spot.

 

mine did the same thing... i had old lights over it. when i changed the it got better in a week or so.
idk if the light was the problem, but its a thought.

 

I noticed it is paper thin. The white part is not thick and fleshy like the rest of the coral. I hope it is not a problem like you all said.