It happens, wouldn't say its common but its also not rare. Some people suggest the change is random but no one truly knows the genetics surrounding the colour changers.
What I refer to as a true colour changer looses black pigmentation and its generally replaced with peach/apricot.
There are others that go through seasonal changes. For example I have a female that is normally brick red but spring through to early summer she will go coffee coloured, losing all black pigmentation on her body for one or sometimes 2 sloughs before going back to brick red.
Will be easy to confirm if you post a pic or send me one and it can be clarified very quickly.
