Yes, it's because LCD screens are typically slower than CRTs and leave more afterimage behind. It's more noticable on high contrast/high colour saturation images. The only possible reason starcraft doesn't do it (as much) is that starcraft is mostly all grey.
Don't worry about it; there's nothing you can do about it except change your monitor!
Don't worry about it; there's nothing you can do about it except change your monitor!