At the time of the incident, Sunderland were leading 1-0 thanks to Asamoah Gyan's first-half opener.
Eight minutes later, Stoke were down to 10-men when Shawcross was dismissed for a second yellow card after a foul on Danny Welbeck.
And with only four minutes remaining, Gyan went on to kill the match off with his second goal of the game.
After the game Cattermole said he was not sure what had happened.
"I think I tried to head it - I'm not sure, I would need to see it again," he stated.
But Pulis was more certain that referee Martin Atkinson and his assistant had missed a clear handball.
Sunderland performance lifts Bruce's spirits
"You go into games and referees are going to make mistakes, like players do, like every one of us in this room will do. You just hope they don't make game-changing mistakes," the Potters boss added.
"I have just seen the television replay. I never see the referee, but I will go to see him today. He has actually got a clear view from the camera angle that I have seen."
Stoke have rued several refereeing decisions in recent weeks, including the ruling out of a goal against Everton and handball in the penalty area by Bolton defender Zat Knight.
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