The Hornets are two games up on the Marlins with two to play, but SU holds the tiebreaker thanks to a doubleheader sweep over VWC two weeks ago.
Coach Kevin Anderson's club found itself in a 4-0 hole to Bridgewater (22-10-1, 11-7) after two innings before battling back with two runs in the seventh and three in the eighth to tie the contest at 5-5.
The Eagles then went back on top to stay with two runs on three hits in the eighth off of a pair of Hornets relievers.
Brendan Howell drove in what proved to be the game-winning run on a single through the left side.
Joe Coleman was 2 for 3 from the No. 9 spot in the order.
Mossman, who opened the day by recording final two outs from the April 8 halted game, allowed five runs (three earned) on three hits and two walks.
He also struck out four.
Shenandoah is back in action on Thursday at 5 p.m. in a non-league contest against Elizabethtown.