Weissert was returned to Triple-A Scranton/Wilkes-Barre following Sunday's doubleheader against the Red Sox.
Weissert struck out two in 1.1 scoreless relief innings during Sunday's matinee, but he'll head back to the minors after serving as the 27th man. The right-hander has posted a 3.60 ERA and 1.30 WHIP in 20 innings over 19 minor-league appearances this year.