Figured it out. During the summer I was stringing and unstringing my bow on a regular basis. I don’t like to leave it strung in the heat, particularly in a vehicle. During the hunting season it stays strung. Just this past week I unstrung the bow while attending a family affair. When I restrung it, I noticed how the stringer and string interact. It’s the stringing/unstringing process that moves the pad. That explains why it’s only on the top limb. I also held the riser down with my sock foot and drew the string, watching the top limb. No evidence of twisting. I don’t have a twisted limb after all.