It also led to some speculation, causing many to question whether there was more to the story behind his seemingly sudden exit. But Gap lead independent director Bobby Martin told CNBC there's nothing else behind the move, and that it was Murphy's decision to exit the company.
In fact, he said Murphy began talking with the Gap board at the beginning of the year about his desire to retire, and the board wanted him to stay.
Read MoreBuy Gap on Murphy's exit: Cramer
He added that Murphy chose his timing to allow for this orderly transition, and because he felt the company is at an inflection point.
"We would have loved for him to stay, but we accepted his very personal choice and appreciate his willingness to stay for the smooth transition," Martin said.
"Gap needs a strategy to move it forward, and [Murphy] didn't think he had the longevity to see it through left in him. We respect Glenn has the wisdom to hand it off at the right time," he added.
Sales at the Gap brand have struggled in recent months, as its product has failed to resonate with shoppers. Sales also have been shaky at the company's Banana Republic brand, though it's recently been performing better. On Wednesday, the retailer said its comparable-store sales for September were flat compared with one year ago.
Martin said Gap hired an outside firm to help it conduct a global search for Murphy's successor. The retailer looked both inside and outside the company, but Art Peck, Gap's current president of growth, innovation and digital, quickly became the top candidate. Peck was informed last week that he would be succeeding Murphy on Feb. 1.
"I think [Murphy] accomplished a lot of what he set out to do," Martin said. "I would say Glenn is probably a guy that's never satisfied."
For now, Murphy said he has no plans for after Jan. 31; but if the right opportunity came along, he would consider it.
"I will probably work again," he said. "I'm only 52, though that's a lot older in the retail world."