John Mayer says he didn’t always feel a sense of urgency about getting people out to see Dead & Company concerts … not even when the group was doing a final national tour in 2023. Now, he does, with a month and a half left on the group’s engagement at Las Vegas’ Sphere. He’s not making any pronouncements about this marking an end of the road for the band — a Grateful Dead offshoot that he formed with three original Dead members back in 2015. And maybe there could be a return to Sphere someday. But for the time being, there’s an expiration date on the visa for this particular Ultimate Trip. “I just don’t want people to miss it,” he says, “because we’ll be out of that building at some point, and you can’t see it unless you’re in that building.”