Courtney Baker-Richardson gave the visitors the lead on 55 minutes but it was a short-lived advantage at Deepdale.
North End hit back on the hour, Daniel Johnson converting from the spot after new signing Jayden Stockley’s cross was adjudged to have been illegally blocked by Roberts.
“It’s hard to see from where I am to be honest,” Potter said in his post-match press conference.
“I’m over on the other side of the pitch, I just noticed that the referee didn’t give it, the linesman did.
“Whether that was a reaction to the crowd or not I don’t know, I need to see it again.
“Connor said it didn’t hit his hand but funny things happen in live football matches.
“Until I’ve seen it I don’t really know.”
The Swans’ manager was impressed with what he saw from PNE who slipped to 18th in the table after a fifth Championship game without a win.
“I think they’re a hard-working team with good qualities,” said Potter, whose side are 13th.
“They used the centre forward (Stockley) really well today and he did a good job.
“They got runners off the side of him and were solid in midfield.
“The conditions weren’t the best for free-flowing football and they press so any technical error they win it back and they’re on the attack.”