"Scharner had something on his T-shirt and showed it to the lads over the other side of the pitch," said McCarthy.
"There is no need for it and maybe that upset the lads. You can lose but you don't need your nose rubbing in it.
"If there were words said between the players, it would have been because of that. He lifted up his shirt, there is no need for it. I get the hump with it."
Scharner argued that the item of clothing was designed by his children and that he will auction it for charity.
The win has moved West Brom up into 12th place in the Premier League table, while Wolves have slumped to 16th.