The cord shouldn't make a difference, since the problem is between you remote and your vehicle, not your screen and your vehicle. Mostly I was just trying to point out that your image transmission signal, as such, isn't the problem. Your signal in general is.
It could be all sorts of things -- a loose connection in your MA or you remote, severe interference, or just the inherent eccentricities of the **** thing. I'd keep an eye on it, but if you can't replicate it, I wouldn't worry about it too much.