Many of the 4,765 North End fans at the DW Stadium wore Grayson masks to mark his fourth anniversary.
Victory evaded his side on the day, Jordan Hugill seeing an early penalty saved in front of the away end.
They had to settle for a 0-0 draw which had followed home wins over Brentford and Birmingham City.
“I think all those masks will be on mantelpieces by now, frightening kids away from the fire,” said Grayson.
“It was nice of the club and the supporters to recognise what we have done in these four years.
“Hopefully in a few more years I am still here taking the club further forward.
“The time has gone quickly, I’ve really enjoyed it, the club has progressed so much in that short period of time.
“I’m proud and privileged to have been manager of this club for four years.
“There aren’t too many in front of me in that respect.”
In a game of few chances, Hugill’s miss from the spot provoked much debate.
His tamely-struck penalty was parried by Latics keeper Matt Gilks who also held the rebound from Hugill.
Grayson admitted that an early goal would have opened the game up and made for a better spectacle.
It was the second penalty Preston had been awarded in 38 league and cup games this term.
Daniel Johnson, scorer of the previous one in the 3-2 win over Blackburn, was on the bench this time.
Said Grayson: “Jordan has been on penalties for the last few weeks and months since he has been in the team and other people haven’t.
“He practices them all week, he was taking them in training on Friday.
“Jordan was disappointed not to see it hit the net but these things happen.
“We’ve seen sides miss penalties against us, Chris Maxwell has saved two or three this season.
“But when you get one, you want to see it buried.”
In what turned out to be a battle of attrition, Grayson said it had not been a game in which the attacking players had shone.
“When you look at things overall, you would say it was the grafters in the team who did very well,” said Grayson.
“Our key players in terms of making things happen in the final third – McGeady, Horgan, Robinson, Hugill, Beckford, Makienok – did not have that cutting edge.
“We had a bit of spark at the start of the second half when we passed it around well but did not test their back four.”