Cheap leather holsters can curl up as they wear out. The corner of the holster catches the trigger when reholstering. The fix is a holster with reinforced mouth so it keeps its shape. But that makes the holster thicker.
I see. My Tucker holsters have an extra "overflap" that helps pull the holster in tighter to the body plus reinforces the mouth. I can't see it ever getting soft in my lifetime. But it does make it thicker.
Of course, if it did, it would just be time to replace it.