He's been positioning himself as close to the Biden campaign for a while, whislt not engaging on the controversial stuff. Even before the debate his people were apparrently spending a lot of energy and favours making sure he'd be the first one called on in the spin room and the first to give interview with the TV networks after the debate. Despite saying that you "go home with the one who brought you to the dance" and a bunch of other metaphors designed to subtly point out Biden's age, while claiming he was backing him 100%, his whole performance was highlighting how different he would be from Biden in terms of ability.

Then, as he was leaving, some smaller press junket reporter trying to ask him questions kept shouting an almost certainly planted question about he "is surely now the democratic favourite to take over" and he could barely keep up the act, shit eating grin beaming from ear to ear and laughing at how well it all went when he thought he was out of frame.

The knives are out and Gavin is already making his play to force the issue, while claiming the opposite, and be annoited as the Biden-campaign friendly candidate.