I took of my pickup guard off of my American P last night (to adjust my truss rod for the first time which went well btw!! ) and noticed that under the p/u guard there is a "hole" about roughly 3/4" in diameter (if my memory serves me correctly) that is located under the pickups (lower part of body if you are holding it in the playing position) towards the neck a bit. Actually, it's about where the thumb rest would be if mine had a thumb rest on the lower part of the body under the strings. There did not appear to be anything in the "hole" and it was roughly 1/2" deep. Does anyone know what the heck this is for? It is not "connected" to anything from what I can tell (like where the electronics are, etc). Could it be something that effects the "sound" or "tone" of the body? Just curious... Thanks!