Different heights

I noticed that my rear is sitting at differentes heights, I mean the pass rear side is around 1/2 inch higher than the drivers rear, am I overacting?, is this normal, or should I check for something? Someone told me oince that the springs have an exact fit and maybe ifthey are not settled correctly this may affect the height.

Thanks.

The springs might be wearing out. No big deal unless they break. However, it might throw your alignment off.