The late blow comes two weeks after Jermain Defoe netted a 92nd-minute equaliser against Gracia's side, while Watford granted Burnley two goals in the last 20 minutes of their Premier League clash last weekend.
"It is another situation similar to the last games, another goal in added time," Gracia told reporters.
"I don't know if it is fair but it is another chance we've missed to get points. It was different from the other games because in those games we conceded goals in the last minute from free kicks, long balls and second balls in the box. Today, it was a challenge where we were soft and after that Huddersfield only had one shot on target today but it was enough for us to lose the game.
"I think they dominated the first 15 to 20 minutes, we tried to defend and create chances on the counter attack but after that we had more possession, we felt better playing more time in the opposition half. OK, we didn't create many chances but we knew today it would be a tough game. We need to keep the same attitude, try to get points in the next game and only be focused on the next game."
Watford host Crystal Palace at Vicarage Road next Saturday as both sides look to solidify their Premier League status for next season.