Paul Heffernan's early opener for Killie was cancelled out by Eoin Doyle, but Hibernian were left fuming when Paul Cairney was booked after he appeared to be felled by Michael Nelson in the box.
Nicholl admitted the visitors could have been handed a spot-kick, but he believes Killie also had good reason to feel aggrieved after Mahamadou Sissoko appeared to be hauled back in the box.
"We should have had a penalty in the first half with Sissoko and maybe they feel they should have had one with Cairney as well, I don't know but I will leave the refereeing decisions to the referee.
"But we are disappointed because we were hoping that after winning at Aberdeen last week we would have got a wee home run starting."
Nelson accepted that the incident could have been interpreted as a foul and sympathised with Cairney, who must now serve a one-game ban after a number of cautions.
He said: "There was contact but how far down he was when the contact was made, I don't know, we will have to see it again.
"As he slipped the ball to the side he was already going down. It could have gone either way but the referee seen it so I am not going to argue.
"But it is probably doubly harsh that the lad got booked as well.
"Just because the referee doesn't think it was a penalty doesn't automatically make it is a dive so I think it is harsh when it happens to people.
"It might lead to the lad getting suspension further down the line so he probably feels hard done by and we wouldn't feel too happy if that happened to us.
"But by all accounts there was a penalty (for us) in the first half when (Mahamadou) Sissoko was pulled back at a corner."