However, Wiltshire referee Lee Probert awarded a stoppage time spot-kick for an off the ball incident between Town's Kachunga and Preston's Hugill.
It was a decision which aggrieved Grayson at the final whistle, making his feelings known to the official as he left the pitch.
“I have seen some bizarre decisions but none more frustrating than this,” Simon Grayson said.
"I have spoken to the players and the referee and seen it on DVD and it's clear Jordan didn't push him. It was a very poor refereeing decision.
"I don't go to see a referee very often but I do when I feel I have a genuine complaint. It's a more than disappointing decision. The referee says he has pushed him and stamped on him but he must have decent vision to see that."
Grayson added: "We had a game plan and the players carried it out well. During the game our goalkeeper has hardly had a save to make.
"We showed character and desire and got something out of the game only for it to be taken out of our hands at the end."