The victory at the John Smith's Stadium followed a 2-1 win at second-place Brighton - leaving them 11 points clear of Huddersfield in third.
Newcastle played the Terriers after Brighton lost 3-0 to Championship strugglers Nottingham Forest.
But Benitez, whose side travel to play-offs hopefuls Reading on Tuesday, said: "Yes, it's good but that's all.
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"We now have to play Reading and there are still a lot of points to play for. We just get ready for the next game."
Newcastle went in at half-time 2-0 up thanks to goals from Jonjo Shelvey and Daryl Murphy before Aaron Mooy pulled one back from the penalty spot with 20 minutes to go.
But Newcastle's leading goalscorer Dwight Gayle, back after injury, sealed the three points with a stoppage time strike.
"I was really pleased with everyone," Benitez added. "Huddersfield have some good players and we knew what to expect from this game.
"It does not matter whether you have a game plan if you don't have the players. The players gave everything.
"We have a group of players who really try. We made some mistakes but it's important we try to do our best.
"Huddersfield are a good team, move the ball well and they will keep pushing."