It's unlikely to be a problem when things are moving. Any time your image pixels are drawn in a way that doesn't match up to screen pixels there has to be some sort of mapping from image pixel to screen pixel. This is called texture filtering. With skeletal animation image pixels are almost never draw 1:1 with screen pixels, so filtering is unavoidable. Nearest neighbor filtering will show more artifacts, linear filtering will produce a smoother result. If you are scaling up or down a large amount, the artifacts may be worse. Scaling down may be worse, since fine details may be lost.
