Hi Kaosu, the stripes are horizontal; kind of like in this pic:
http://www.getahugetank.com/images/betta-female.jpg
There are times when she's normal coloured (like when I first turn on the lights), but she turns stripey when I come close to the tank to feed/watch her- maybe she's afraid of me?? :S
The tank is filtered, 80F and gets 50% water changes per week. The Petsmart I got her at kept their bettas near the door-so she may have been exposed to drafts. She's still active and eating; her activity level varies though and she likes to spend a lot of time near the bottom in/around the plants and sometimes she clamps her tail. Seemed to be out and about more since I put in a baffle today (she was quite curious about that)- will see how she is tomorrow
I'll see if I can get a good pic where she isn't a fuzzy blur haha.