Acts 6:8 - Stephen is described as "full of grace" (πλήρης χάριτος)

In Acts 6:8, according to some manuscripts the Greek text states, >Στέφανος δὲ **πλήρης χάριτος** καὶ δυνάμεως ἐποίει τέρατα καὶ σημεῖα μεγάλα ἐν τῷ λαῷ. (NA28 ) which is translated by the NABRE into English as, >Now Stephen, **filled with grace** and power, was working great wonders and signs among the people. The Greek πλήρης χάριτος literally means "full of grace" (cp. John 1:14 ). In the Vulgate, St. Jerome translated that Greek phrase into Latin as *plenus gratia*, the equivalent of *gratia plena* in Luke 1:28, the only exception being *plenus* declined in the masculine gender referring to Stephen and *plena* being declined in the feminine gender referring to Mary (and the word order which is inconsequential). That being said, it is reasoned by Catholics that the virgin Mary was sinless because she is *gratia plena*, "full of grace." Can it be also said of Stephen that he, like Mary, was born without original sin and that he also never sinned, since he too is described as being *plenus gratia*? Why or why not?