This is going to be a digitizer flex problem. Most likely case--you've allowed the digitizer flex to fold slightly between the digitizer and the LCD, it *seems* like it was designed to fold that way. The weight of the digitizer on the flex over time has made a crease which destroys function.
On your next replacement, make sure that 100% of the digitizer cable slides through the space between the LCD and the frame--it will fit!
jessa