"He did as good a show as he's ever done," Fred Champoux, a saxophonist in Gans's band told the Las Vegas Sun.
"He was in top health. Before Wednesday's show we had a Bible reading and then he was discussing with us a book he was writing with a friend and how positive the book was and how amazing it was going to be when it came out," Champoux added.
The 52-year-old entertainer, noted for his impressions of everyone from Michael Jackson to Tony Bennett, was due to perform again at the Encore Theater on Friday, but was found at his home in Henderson, Nev., around 3 a.m. that morning by his wife, Julie, a Wynn Resorts spokeswoman told PEOPLE.
Gans's manager Chip Lightman told the Las Vegas Review-Journal that he had texted with the singer – whom he described as a "health nut" – on Thursday.
"Everything seemed fine. The only difference was, on his day off, he would usually run errands and stuff, and he was exhausted. He hadn't slept well the night before. He laid down in the late afternoon."
It was later that night that his wife woke up and "didn't feel him breathing," Lightman told the newspaper.
Though musician Champoux had said Gans recently battled a cold, "Wednesday night he was in top form and did an amazing show. ...
"There was no suspicion anything was wrong, not a clue that there was a problem," he added. "No indication at all that anything like this could happen."
According to the Review-Journal, the athletic Gans was a onetime minor-league baseball player who had undergone surgeries on his neck, shoulder and wrist over the years, most recently in November.
While autopsy results have yet to be released, local columnist Norm Clarke did point out a twist on Wednesday night's performance. He noted that Gans nearly regularly ended his shows with the medley "Apollo," but that night he made a change, closing with a Bobby Darin favorite, "The Curtain Falls."
Wrote Clarke, "No one will ever know for certain, but just maybe Gans knew something was amiss."