I thought that everyone knew that baby hair often changes colour dramatically. My own daughter was born with gingery hair and I thought "YAY! a redhead" But by the time she was three or four months old she was a platinum blonde. Still is. Gorgeous.
It literally changed in a week. Maybe it can happen, but i've heard various other stuff that would support something was going on - i'm aware they broke up earlier than on the TV show for a start.