Again, this is tough to say without seeing you but here are some thoughts.  In general, as we age, the upper lip gets longer and loses it slight concave (like a gentle ski jump) shape.  It gets flatter.  If someone is filling those lines and isn't careful to preserve that contour than it may make the upper lip look heavier and longer which could make the lips themselves look smaller and more compressed.  A good injector is careful to keep that contour or tries to recreate it if it's been lost.  In some people, it really is almost impossible to get that curve back. Here is some more info on lips. In that situation, your doctor could talk to you about that problem before the treatment.   Hope that makes sense.  Dr. I