||between the top of the pull and the "cup" portion. With use the pivot pins and/or the holes they ride in start to wear, the handle loosens slightly, and as the top gap gradually closes, it eventually starts rubbing. Tends to be worse on the driver's side for obvious reasons.
The "right" way to fix this would be to use an oversized pivot pin (could probably be made from steel rod)and bore out the holes to accommodate (even better if bushings were used to buffer the movement and wear). This would need to be a precise boring process to ensure that the original pivot angle is maintained. I haven't heard of anyone doing this. I studied the problem several times in the past, but don't have the right equipment. Would be great if someone offered this as a service, especially since new handles are no longer available.
You are correct that the gap does tend to get smaller when primer and paint are applied. When repainting it's important to sand off all the old paint, and it is helpful to open up the gap a little more than needed to compensate for inevitable wear. I've done this on several sets of handles. Its important to start with handles that have minimal pivot slop (usually low mile parts). The movement isn't always very apparent because the spring tension may mask it.