It's not in your head my friend.
I almost didn't buy the X3 after test driving the car... I thought to myself, "this is a premium car and they don't know how to modulate drive-by-wire"??
I started researching aftermarket fixes for the problem and figured I could fix the problem until BMW fired the junior engineer who did the original programing.
Well by the time my car was built BMW had fixed the design fault and my car was delivered with a nice smooth linear accelerator.
Maybe you just taught yourself to use the non-linear accelerator.