Female Betta Fish Stripes?

I have had this particular Betta for about 3 months and she is a whiteish red and she has horizontal stripes. I've heard that horizontal stripes mean stress but she's had them for all three months and they're almost the same color as her. Could it be that she is just a striped fish? I have two Betta and they are in tank made for Betta fish that has a divider so that one can have two at the same time.