Ant McPartlin reflected on his time in rehab as he made a joke when the pair announced it had been two years in the making for filming.
The show started with Ant and his best pal Dec Donnelly introducing themselves, and while Dec admitted it had taken a while to film, Ant pulled a face and made a joke about being to blame for the delay.
Dec, 44, said: "It's taken us a little while," before Ant, 43, replied: "Sorry about that," making reference to his year-long hiatus from TV, during filming for the documentary.
Ant and Dec fans were going crazy on Twitter as they noticed his little joke, praising the presenter for being open and positive.
One fan tweeted: "Love how they can make a joke about the past couple of years now #AntAndDecsDNAJourney".
Another laughed: "#DNAjourney just brilliant @antanddec A loved the 'sorry about that' comment.."
And a third shared: "Absolutely loving @antanddec and their #DNAjourney - laughed out loud a lot so far! 'Taken us a while.... sorry about that'".
The pair began filming for their documentary - which sees each of them meet long-lost family members - in 2017.
At the time, TV star Ant had checked into rehab after admitting a drink and drugs problem.
He then decided to take time off from all TV commitments while he sought help, including absences from Britain's Got Talent and I'm A Celebrity.
Early last year - in March, the showbiz star was arrested on suspicion of drink-driving after a crash.
The TV host lost control of his black Mini on a roundabout and went head-on into a green Mini containing a couple and their young child.
In April he was then fined £86,000 after pleading guilty to drink driving and issued an apology.
Ant has since returned to TV after treatment, making his comeback on BGT this year, while next week he will host I'm A Celebrity 2019
*Ant & Dec's DNA Journey continues tomorrow on ITV
