Hartley was one of four try scorers for the hosts as they started their campaign with a bonus-point win at Franklin's Gardens.
"If you look at the first half, we scored four tries off a lot of turnover ball which came from solid defence," the hooker told the club's official website.
"Then in the second half we were on the back foot in defence. However it's the first game of the season and a pretty good way to start."
Northampton continue the season on Friday when they make the trip to Harlequins.