Curbs told Sky Sports, "We deserved to be the first team to win here and I think Sven would agree with us.
I thought it was (offside). I think the linesman said he wasn't interfering in the first phase of play, and yet he's standing in the six-yard box.
"I think all of us are a bit bemused by it (the offside rule). Sometimes you get the rub of the green but it has gone against us here."