The 29-year-old has failed to replicate the form that earned him a multi-million pound move to Wolves but he netted his side's equaliser in the last minute of their 3-3 draw with Brighton & Hove Albion at the weekend.
However, the former Cardiff City centre-back revealed that he was disappointed that his first goal for the club did not earn his side three points.
Johnson told BBC WM: "I'm disappointed it wasn't the winner, I think the decision for the penalty was very harsh.
"But we showed decent character to come back and thankfully I got my head on a cross finally."
Wolves are currently in 15th place in the Championship table.