A Clive Platt goal after a blunder by goalkeeper Jake Cole was all that separated the two sides at Sixfields, where Northampton made it an impressive nine home victories in ten outings.
But Cobblers had to work hard to secure all three points against a Plymouth side who did more than enough to have taken a share of the spoils in their bid to stay clear of the relegation zone.
Sheridan was angry over Northampton's winning goal and fumed: "It was ridiculous and anyone who was at the game watching it will have said what a ridiculous decision it was to give a goal.
"It was a clear foul on our goalkeeper and the referee is the only person in the ground who hasn't seen it, but he probably hasn't ever played football so he doesn't know.
"They should get ex-players in and people who know the game to referee these matches. We played some decent football and were right in the game but the goal set us back and we couldn't get going again after that."