Baltimore author Eric Puchner turns 55 next week, but he got the early gift of a lifetime on Tuesday: His new novel, “Dream State,” was named Oprah Winfrey’s latest Book Club pick.

It’s a secret the Johns Hopkins associate professor and Writing Seminars department chair has had to keep for some time — even from his kids.

“I didn’t feel like I could necessarily trust them to keep this secret for months so I didn’t tell them,” Puchner said with a laugh on Tuesday morning, while riding the train to New York ahead of a reading event. (His daughter, a college student, slept through the reveal on “CBS Mornings” anyway.)

Released today, “Dream State” is Puchner’s fourth book. Largely based in Montana, the novel spans five decades and focuses on a love triangle between a future bride, her fiancé and his best friend. It’s a fictional story initially inspired by a nightmarish wedding Puchner officiated, where attendees came down with norovirus.

Puchner’s publicist didn’t tell him about the selection or that Winfrey would deliver the life-changing news — just that he had to take a call at a certain time. So Puchner left a Johns Hopkins meeting early and headed to his car.

“I get terrible reception in my office,” he said.

The call came from an unlisted number but the voice on the other end quickly dashed any mystery.

“I picked it up and it was Oprah Winfrey,” Puchner recalled. ”I was flabbergasted. I almost dropped the phone.”

“Dream State” is the 111th pick for Winfrey’s famous book club, which began in 1996 and has catapulted numerous titles, new and old, to the top of bestseller lists. “Oprah’s Book Club”-branded editions — including Eckhart Tolle’s “A New Earth” and Cormac McCarthy’s “The Road” — sold more than 22 million copies over the span of a decade, according to a 2011 Nielsen report.

Puchner had only praise for Winfrey, the former WJZ anchor-turned-billionaire media mogul whom he described as a careful and thoughtful reader.

“She asked me really smart questions,” he said of their recent sit-down interview, filmed late last year and posted Tuesday to YouTube. “All of the sentences that she had plucked from the book that were her favorites are also my favorites.”

In the interview, Winfrey complimented Puchner for his “beautifully written characters.” She described “Dream State” as “a real page-turner and an emotional roller coaster” about love, friendship and how relationships evolve.

This sort of attention is “brand new territory” for Puchner, whose previous books include the 2010 novel “Model Home” and the story collections “Last Day on Earth” and “Music Through the Floor.”

“I’ve been toiling in relative obscurity for a long time. … It’s just incredibly gratifying and also surprising. I didn’t expect it at this point in my career,” Puchner said.

Puchner, who attended Calvert School, describes himself as “a slow writer” who labors over his sentences. He worked on “Dream State,” which was originally more than 800 pages, for five years.

Fans will be heartened to hear, however, that Puchner is in the “very early stages” of a new novel. “Just don’t ask what it’s about,” he said with a chuckle.

Understandably, he’s about to be busy for a while, with a schedule that includes his normal teaching duties and “Dream State” reading events across the country. At 6 p.m. on Saturday, he’ll appear at Bird in Hand in Charles Village for a chat with author Danielle Evans.

“I think it’s going to be quite crowded in there,” he said, “but I don’t want to jinx it.”

After such a momentous morning, that feels like a safe bet.