If you take off your bra and the roll disappears, then it's the bra that's the problem, not your figure. I suspect if the bra was sitting lower on that model, there'd be no roll. This is one of those "you need a smaller band and larger cups" fit issues.
A roll will start appearing on me when my bra is wearing out, making the band looser and prone to creeping up in the back rather than staying put. Case in point: a few months ago I thought it was time for another bra fitting due to weight gain, because my bras seemed to be creating unsightly rolls not just in the back but the front and sides. So I went to have a fitting and lo and behold, I am still in the exact same bra size -- it's just that the bras needed replacing because they'd stretched out too much in the band. Same size, new bra, exact same style/brand -- made all the difference.
My DD gets this issue even more so than I do, because she's got a much tinier waist. She's quite busty with broad shoulders narrowing down to a tiny waist like a triangle, whereas I'm more like a rectangle. We go bra shopping together so we have someone to check our backs etc for fit. We long ago figured out that the bra band needs to sit lower to be most flattering in the rear view. Though she's larger than me (wears a size L tee and I wear a size SP tee and is 4 inches taller) she takes a 32 band and I take a 34. The difference is the tiny waist. If she puts on a 34 band it rides right up in back-- and produces back rolls.
