Speaking to the club website, Bunn said:"I didn't see anything untoward with the challenge. "I turned to speak to Tony (Mowbray) and he said the same thing.
"I've spoken to Michael (Doyle) and he said he didn't do anything that deserved a red card, so it is something we will have a look at.
"It killed us, but we still made some basic errors and when you are chasing the game against a side as good as West Brom they will punish you.
"We made a sluggish start and allowed Bednar around the back of us to get the cross in for the first goal.
"We then clawed our way back into the game and started the second-half quite brightly until the red card and that changed the game."