The Hornets won 1-0 at Vicarage Road.
Asked further about Deeney, who was making his 300th league appearance for Watford, Gracia said: “I'm very happy with him. I don't know what happened in the past. I see him working a lot and he's scoring important goals in this moment, but I've spoken about that a lot of times.
"Training is not only important if you score or don't score goals, it's important for us on the pitch and off the pitch."
Deeney's goal was set up by substitute Will Hughes, who made his return to first-team action following a three-month lay-off with a hamstring injury.
“It's good news for us," Gracia said. “Not only Will, Miguel Britos only played a couple of minutes but he's again with us. I'm happy for them because they have been injured for a long time and now we have more possibilities, more options to choose from."