The goalkeeper shoved Pieters during the argument, which occurred moments before Peter Crouch restored his side's lead at the bet365 Stadium.
Charlie Adam also kicked a seat after being taken off with the score still at 1-1, but Hughes believes that the passion comes from the high expectations his players have of themselves.
"If you're demanding of yourself and teammates that's what happens," he told reporters.
"It can be a difference of opinion or players getting taken off, sometimes they look at it from their point of view whereas I've got to look at it from a team point of view and how the game is panning out.
"I haven't got a problem with it, it's not an issue within the group. I expect and demand they challenge each other every time we play."
Stoke's win sees them end a four-match losing streak to move up to 11th in the Premier League table.