The Scottish striker netted in the 91st minute to snatch all three points at the death at Highbury on Saturday afternoon.
Introduced from the bench in the 86th minute, Aitchison was presented with an aerial ball in the box courtesy of James Norwood and glanced a header into the bottom right-hand corner to send the travelling Reds fans into raptures.
Stood on the touchline, waiting to be introduced, the 22-year-old felt he would he come on and make an impact.
"I saw there were five minutes left and I thought, 'just try and be busy'. I had a feeling before the game I was going to come on and score.
"It was down to the boys. It was a tough game, we were a bit under pressure but I thought we deserved it in the end."
There is always a danger that when chances are created and aren't taken, it may not be your day out there. Especially considering the form of the hosts, unbeaten at home all season and falling to defeat just once in the league.
However, the former Celtic man did not doubt the side's ability to make the breakthrough in a stubborn affair on Saturday afternoon.
"I thought in the first 15 minutes we were brilliant," he praised. "I thought Cadds [Nicky Cadden] and Jord [Jordan Williams] put in some unbelievable balls, they were just a yard or two away from us.
"Never. I never doubted it. Nors [James Norwood] and Coley [Devante Cole] are on fire, so no, never doubted it."
Aitchison's goal secured all three points for the Reds and marked three away wins on the spin, keeping clean sheets in all of them.
Michael Duff's men are now six unbeaten in the league, but Aitchison emphasised the importance that the team recognise that the campaign is still fresh.
"We need to remind ourselves that it is so early in the season. Like the gaffer says, game by game and that's what we do; we don't look too far ahead.
"In the last five minutes, it shows we can go right until the end. I think sometimes we have got goals early and maybe we've not been tested right until the end before. It just shows that we can score at anytime."
