"But if he has, then maybe there is a chance to make a bit of a statement here."
Phoenix have confirmed they will appeal the straight red card given to Sigmund and ask Football Federation Australia to erase the booking.
Herbert was also incensed by other refereeing decisions in his club's first loss of the season.
Wellington's Jeremy Brockie appeared to take a 2-1 lead in the 59th minute when heading a goal, only to be ruled offside.
And just nine minutes later, Adelaide's Cassio goaled from an offside position.
"You have seen the video footage, write it yourself, I probably don't need to put words in your mouth," Herbert told reporters.
"At the end of the day we have got an opinion and sometimes we can't voice it and I think that is to be respected.
"But all we ask for, is there an equal sort of line across the board?
"I think Jeremy's goal was a great goal.
"I thought Cassio's goal ... that is offside."
-AAP