"The multiples that were being offered on the business itself were very attractive," he said. "As we looked forward, the competitive nature of the market made us believe that we might be better off moving our investments to more profitable business lines."

They also took into account rising labor costs, and operating margins getting squeezed by competitors such as drugstores and "dollar stores" selling products like beer and chips. And they wonder what the future holds for gasoline demand for vehicles, in the face of emission standards and the push to develop electric vehicles.

Noco also took stock of its competition.

"You're facing large consolidators who have all kinds of scale, both in how they buy merchandise or gas, but also in terms of their operating costs," including information technology and maintenance infrastructure, he said.

"My view is that you're going to see most store operators be either single-site operators or over 100 stores," Newman said.

And while companies like Marathon are a driving force in convenience store consolidation, private equity has also poured into the industry over the past decade, driving more deals, he said.