If you have seen no change in behavior or eating habits its normal to think it could be stress. When I got my first betta Junior I thought this color change was due to stress but as time progressed I noticed it was just his normal color and now he is a deep red. I'm sure that is because he eats color enhancing pellets. Not sure how long you have had her but just make sure she has plants or hiding spots that she can go and feel safe secure. Give her time to adapt to her new environment.
Last edited by Kenny G; 06-30-2012 at 11:16 PM.