trust me, I mess with enough of these to know, when it is bigger, it is sandwiched. You may think 1mm - 1.5mm isn't much, but it is. Especially because exactly what I am talking about occurs. When the lens is too large to fit be it 1mm or 5mm, what happens is the lens is bent or flexed to fit in since you are essentially "forcing" it to fit. When that happens, it transfers that flex across the lens in different areas depending on the stress point, which in turn distorts the natural optics of that lens. Any bend will introduce a level of distortion when it isn't meant to be there.
I was cutting some polar juliet lenses once and had that happen, and that is how I figured it out. They fit, but were tighter by a bit more than they should have been. When I was tightening the screw down on the one side, I was in front of my LCD monitor and noticed the rainbow looking waves changing as I tightened or loosened the screw. So I can tell you, there is an effect.