After being told that his betrayal hadn't been revealed to the Saviors, Dwight thinks he's home free. However, Negan might have other ideas. A few episodes back on The Walking Dead season 8, Dwight finally made his brewing face turn overt, killing several Saviors and outwardly helping Alexandrians survive. Unfortunately for him, fello Savior member Laura escaped, presumably to return to the compound and reveal his actions to the boss. However, in Sunday night's episode, Dwight encounters some Saviors, and is surprised to learn that Laura seemingly never returned to base. Thus, Dwight is still considered loyal.
While Dwight clearly hasn't changed his mind about wanting to bring down Negan - he lead the armed group of Saviors away from a vulnerable Tara after all - he did opt to return to the compound, just in time to hear Negan finish regaling his followers with their latest offensive strategy: melee weapons coated in the blood and guts of the infected. It's unclear if Negan noticed Dwight's arrival, but they didn't have a one-on-one meeting before the episode ended. Dwight obviously assumes he's okay to make nice with Negan, and perhaps gather intel for his new uneasy allies as to what the Saviors are planning. In thinking that though, he's likely underestimating Negan.
As brutally violent as Negan often is, the man knows how to lead effectively, albeit in his own sick way. He didn't get to where he is in the apocalyptic afterscape by not being smart, and has been shown to also be an effective manipulator in addition to his prowess in combat. Which is where the next possibility comes in. It would make zero sense for the uninjured Laura to go anywhere but straight to Negan after escaping Dwight, and the Saviors that tell Dwight she hasn't been seen are normal rank and file. Thus, it's quite possible that she did go right to Negan, who - after his initial wave of anger and surprise passed - instructed her to lay low, and let him deal with "D" in his own strategic way.
As Negan has said more than once, he sees people as a resource, which is why he rarely plans to kill more than one of them at a time. With the knowledge that Dwight is working with Rick's group in hand - and Dwight's lack of knowledge that Negan knows about his betrayal - Negan could have Dwight monitored closely, and perhaps use him to learn the location and/or plans of the good guys. Additionally, he could feed Dwight false information, in the hopes that Dwight will then carry that bad info back to Rick, setting the latter up for an ambush.
On the other hand, it is obviously possible that none of that is true, and that Negan truly is in the dark about Dwight. Even if that's indeed the case, Dwight is playing a dangerous game by returning to the Savior compound, as Laura could theoretically appear at any moment to reveal what he's done. If that happens, Dwight would be just about as royally screwed as if Negan had known all along, due to being alone behind enemy lines with no backup. Either way, Dwight may not have long to live.