No she's actually not a dragon scale. Dragon scaling is much more prominent than that, that's just her regular iridescence. However Betta's can have different "skin" tones like my girl Mystique who looks like a larger version of your girl has a red head while your's has a black head. It turns more blue when she's stressed out, I see her stress lines which indicates that she lost color that's all. It's a normal thing for them to do and so now you'll easily be able to see when she's stressed.
My girl Mystique normally has the red head but it fades to a dark brown, almost black when she's stressed out so...sorry, your girl isn't that unique lol but she is beautiful still! I'm sure she's just chock full of personality too!!