Coris Wrasse hibernation?

35% Off ! All WYSIWYG fish and corals
I have a Coris Wrasse he started changing colors very slowly, He started to hide in the sand for about a week at a time, then he disappeared in my tank for over almost two months.
I thought he had perished.
Just this weekend I saw his tail sticking up out of the sand and fished him up with my net. to my surprise he is alive.
However, he is very pale in color. Has anyone heard of this "Hibernation" period for the color change before?
He was well adjusted in the tank prior to this.
Any explanations?
Curious Coris Owner...