I think grip is evolutionary. What you think is backing off or "loose grip" is still harder than when you first started shooting. It is relative to your experience/time on your gun. Over time your grip actually gets harder because you become more aware of specifically where and how to grip your gun to track sights/dot and still leave your trigger finger relaxed. Eventually you can get to the point where you can be gripping too hard or too much in the wrong places or without the correct proportions with your strong/weak hand. At this point, you "relax your grip" and become confused because you shoot better. In reality, you are gripping just as hard as you once were, its just more refined now. I would say you are at that point and that's a good thing.
I think you're onto something.
Also: people are continually victims of their own frame of reference. If a guy has big, powerful hands, his relatively relaxed grip will be vice-like compared to the guy (or girl) with small, weak hands.