Gap springs in dynamic analysis

Hello,

I am conducting tests with gap springs in non linear dynamic analysis (ase) and have noticed that when a spring is applied at a quad element node or links two nodes, support forces seem to appear before the defined gap closes. I would like to better understand the behavior of these springs in dynamic analysis.

Please refer to the models below, where a 350mm gap is defined, yet reaction forces appear prematurely.

I appreciate your insights in advance.

Best regards,