Steve Bruce had a go at him when he initially flagged but, to his credit, the lino immediately admitted that he'd got it wrong and appeared to apologise. Brucie then acknowledged the linesman - mistake spotted, corrected and resolved in a trice. Good officiating throughout. However, I do think that Campbell got away with a lot of snide late kicks and flicks before he was eventually booked.
Warnock was only moaning so that he didn't have to ask question about why his side was so defensive and that he was tactically out thought by Steve Bruce.
Neither Savage or Shearer on MOTD thought it was a foul, so shows Colin was just looking for excuses that Campbell was an arse, and just looked as if he wasn't interested to score just wind up the opposition.