I've found that some of my guitars have a lower string action at the 24th fret vs their 12th fret height. I adjust all my guitars to have the proper neck relief, some guitars progressively get higher action as you play higher up the fret board which seems normal. But a couple of guitars that i've owned have the opposite. For example i've had 2 different Schecters that have 1.5mm action at the 12th and around 1.2mm at the 24th fret. Is this because the heel of the neck has developed a rise?