Avalon ,discoloration of ceramic tweeter

I have the Avalon Opus, but the tweeters have a light brown discoloration in the center.
The spots are about half a inch.
The dutch importer of Avalon told me that it has been caused due to ver loud playing , for a short time.
And that it`s no problem , no warranty issue.

Will the tweeters cause problems in the future?
Thanks for the responces.

I have never played them loud.
Bought the Avalons used , with 6 months warranty (ended in May).
The dutch importer did listen to the tweeter, and it was sounding fine .
His explanation is similar to Aljordan`s.
If you look at one of my systempictures you see a new 30 mm new thiel tweeter with s slight coloration this one came straight new out of the box and plays fine