Keith Hill's men followed up their slender victory over Bury last weekend with another three points against the Gulls in a tight contest.
Scott Hogan's deliveries from the right provided Dale's most potent threat during a first half of few clear chances, the visitors going closest to scoring when Billy Bodin raced into the area and fired towards goal from 10 yards, Javan Vidal's challenge diverting the ball onto the roof of Josh Lillis' net.
There was another escape for the home side when Lee Mansell's free-kick was flicked on by Bodin and Karl Hawley's improvised near-post effort flew just over the bar.
Torquay goalkeeper Martin Rice pulled off a fine save to push Ollie Lancashire's header over the top early in the second half, but the visitors rode out a period of pressure and went close themselves when Bodin's cross was met by Aaron Downes, his header flying straight into Lillis' arms.
The game was settled 13 minutes from time when Henderson dispossessed Krystian Pearce and exchanged passes with Hogan before slipping a shot past Rice.