In his first game against his former club since moving from The Hawthorns in January, Long was awarded a spot-kick in the 32nd minute when he appeared to trail his leg in a coming-together with West Brom's Craig Dawson.
Referee Chris Foy hesitated before pointing to the spot, with Liam Rosenior nodding in the rebound after Nikica Jelavic had seen his kick saved by Ben Foster.
Long then rubbed further salt into West Brom's wounds before the break, tucking the ball home from 10 yards after getting on the end of Curtis Davies' flick-on.
Visiting coach Pepe Mel was less than pleased with the award of the penalty, but Bruce moved to defend his forward.
"It might be a soft penalty but Chris Foy is less than 10 yards away when he gives the decision so maybe he's seen contact," Bruce said.
"Longy's never going to dive, he's as genuine as they come but when you move as quickly as he does then the slightest little tap you're going to go over because you're travelling at such pace all the time.
"He was instrumental in getting us the penalty and obviously he's got a terrific goal.
"It's always a bit surreal playing against your old club, it's a strange sensation, but I'm sure when he's sitting down tonight he'll enjoy the day."
The only negative for Bruce was Long's withdrawal 12 minutes from time after he suffered a knock, but he is hopeful that the injury will not prove to be too much of a problem.
"We'll see how he is but we don't think it's too serious," Bruce added.
"We think it's a kick to his knee but for him to come off there must be something wrong."
