Yeah 'ghost touches' can be many things. I'd make sure any software is up to date and if you've added any apps recently you could try uninstalling them.

You could also try removing the screen protector (if you're using one) and give the screen a really good clean.

I mean you're probably right if the phone's old and had plenty of use might of just had it's time but it could also be something quite simple.
乂º◡º乂

Sadly I agree with you. Plus I know with Samsung phones when they have a new model come out they make your phone act up for a few months trying to get you to upgrade. They definitely don't want phones to last anymore.