Sasha has been criticized in the past for having shallow edges in her spirals. She's probably worked on deepening her edges with the bonuses for changing edge. I have noticed that they curve much more recently- the lowering of the upper body could be her mechanism for shifting her weight around her foot. Some skaters adjust their hips and free legs with the same effect, but Sasha couldn't possibly do that without sacrificing some of her amplitude.
While the above is possible, It's also possibl that as Sasha has strengthened her lower back, she's lost some of that flexibility that made it easier for her to hold her back more upright a la Sentimental Waltz, posted on one of the first pictures in this topic. She still looks good through her upper body even if it isn't quite as lifted of a line.
Personally, I'd rather see a slightly droopy spiral than have anybody risk further back injuries, which can be debilitating. Nevertheless, the Sentimental Waltz picture remains my favorite photo of Sasha.