The hosts hit the post through Rory Delap and saw their own crossbar rattled by John Arne Riise before Jon Walters broke the deadlock in the 80th minute, diverting Matthew Etherington's effort home.
Delap then doubled their advantage seven minutes later, nodding in an Etherington free-kick.
"It has been a great start to the season and we are very, very pleased," Pulis said.
"But we know in football that it can change so, so quickly and we will just keep our feet on the ground and the players will keep working hard.
"We want the supporters to enjoy this period and really get behind the lads, and they have been doing that, so it is smashing at the moment.
"But if you take your eye off the ball in this game, then it can soon fall and crumble away."