But Finn Kuqi says Paulo Sousa's team have moved on from the disappointment.
"We've put that behind us and want to get on another run, we'll finish the season on a high and see what happens," Kuqi told BBC Sport Wales.
Swansea remain fourth after the Vicarage Road win, seven points behind second-placed West Brom but nine ahead of seventh-placed Blackpool.
"It was disappointing last Saturday the way the game finished because we thought we should have won the game - again the referee did nothing in our favour," said Kuqi.
"But we rallied the team. We knew we couldn't pass as much at Watford because of the quality of the pitch so we decided to go more direct.
"Every time we got the ball in the box we looked dangerous.
"I'd had two chances with the head but it was third time lucky.
"I got the ball in the back of the net and got the three points, but it was a team performance and man-of-the-match was Dorus de Vries."
Swansea keeper De Vries bounced back from his unusual injury-time error at Forest with another commanding performance to keep his 20th clean sheet of the season.
The Dutchman is chasing Roger Freestone's club record of 22 shut-outs.
"It was a sweet victory away from home, 1-0 and another clean sheet and a great team effort so a big hand for the guys," De Vries told BBC Sport Wales.
"They were giving us all sorts of balls inside the box and playing at a high pace, but we responded very well with a great goal from Kuqi.
"I was delighted with my saves, especially after the loss to Forest - you want to be there when your team needs you."
Swansea remain the masters of the one-goal victory, having scored fewer (31) than anyone in the Championship and conceded the least (23).
Source: BBC Sport
Source: BBC Sport