Reid headed home Hourihane's 82nd-minute free-kick to ensure Rovers tasted derby defeat for the second time in four days following their midweek reverse at Bristol City.
Sheridan said: "I think the delivery made it. It was a great ball in from Conor and Reuben was in the right place at the right time and after the goal you could see our confidence."
Argyle had come close to opening their account when defender Neal Trotman's 64th-minute header was cleared off the line, before Rovers goalkeeper Steve Mildenhall denied Marvin Morgan at the far post following another superb Hourihane set-piece delivery.
Sheridan said: "The most pleasing thing was the result. It was important we got three points. We've got two home games and we are looking to get maximum points from them.
"I don't think we played well in the first half. I said to the players they need to get out there and hit the ground running, especially at home, because we know the crowd will get behind us but I thought we were a bit flat first half, a bit direct.
"I would like us to start playing from the back and I said to them at half-time 'don't be frightened to throw it out to the full backs every now and then' because it can create and it stretches the game. I told them to express themselves a little bit more.
"I thought we played with a lot better tempo in the second half, we had the enthusiasm and will to win and the crowd got behind us. I think we deserved to win the game after the second half but I thought they were the better team in the first."
- Sports & Recreation
- Neal Trotman
- Steve Mildenhall