Does lip augmentation eventually elongate or stretch out the philtrum due to gravity, time and age?

Why do some people who have lip injections end up looking like they have a hugely stretched out philtrums? What is going on here? I can think of several celebrities who's upper lips don't look right, as well as notice people on the street with hugely disproportionate philtrums. Is this caused by injecting too many times, improperly done injections, too much injected causing philtrum to stretch? Is this the result of having lip injections when younger, coupled with time, gravity, and age?