No, there is no problem at all with long term use.
We are not scientists :) but we did plenty of research about the subject, and this is what we learned:
When you apply force to bend acrylic just a couple of degrees, the case with our rulers, the “atomic bonds” are stretched, but none are broken, the deformation is elastic. Upon relaxation of the force, the atoms return to their original equilibrium positions. This is called “Tensile Spring back”.
Therefore, you can bend the two Acrylic plates, which are part of our pin assembly, practically indefinitely, and they will always come back to their natural, original shape, since the pin assembly prevents these two plates from bending past the breaking point of the atomic bonds.
We consider this one of the most important aspects of our design, since it is the best way for self-retracting needles without springs or the use of moving parts such as guides or hinges that would wear out over time due to friction.