The goalie has been reassigned to the Toronto Marlies, the Toronto Maple Leafs announced on Sunday.
Hildeby was initially called up to back-up Cayden Primeau on Saturday against the Buffalo Sabres while Anthony Stolarz received a rest day. Joseph Woll is still working his way back to the ice after a personal leave of absence.
Hildeby had a 3-3-0 record in the National Hockey League last season and posted a .878 save percentage. The 24-year-old signed a three-year extension with the Maple Leafs on Sept. 2.
Toronto returns to action on Tuesday, hosting the Calgary Flames.
