The striker was offside as he gathered a through ball from Kevin Thomson.
"I stuck it away and thankfully the linesman hasn't put his flag up," Heffernan told BBC Scotland.
"There's plenty of times in the season when you're onside and the linesman will stick the flag up, so maybe that was a bit of luck we deserved today."
“When you play Celtic, if you can get a point, you will always be happy enough. But, when your winning for so long, you're disappointed that you didn't pick up three”
Pat FenlonHibernian manager
Hibs have only lost one of their last nine games as they have recovered from a poor start to the campaign.
"Early on in the season, they weren't maybe getting the results that performances deserved, but the last five or six games we've picked up some good wins and that was a good point today and long may it continue," said Heffernan.
It took a superb James Forrest goal after 77 minutes to ensure Celtic did not suffer their first domestic defeat of the season.
"We're happy with the point in the end, but we obviously managed to get ourselves in front early on and we nearly hung on," said Heffernan.
"Celtic had a lot of possession and created a few chances. I thought our keeper and our back four were magnificent to a man.
"If you had given us a point before the game, we would have took it, so all in all we can't complain really."
Hibs suffered injuries to defender Ryan McGivern, who was off the field as Forrest scored the equaliser, and Michael Nelson.
Manager Pat Fenlon reported: "I think Ryan is not too bad, but I think Michael has a problem with his cheek, so we'll maybe need to get him an x-ray and see where he is."
Fenlon was delighted with his defence, picking out goalkeeper Ben Williams for special praise.
"It was a tough game," he admitted. "I thought there were spells in it when we did quite well.
"A great start obviously with the goal then Celtic put us under a lot pressure and created some chances.
"But, again, we got some great blocks in and Ben made some terrific saves.
"When you play Celtic, if you can get a point, you will always be happy enough.
"But, when your winning for so long, you're disappointed that you didn't pick up three."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.