A source says it was a cold that sent the former president home from an election-monitoring mission
Credit: Issiam Rimawi/Anadolu Agency/Getty

Former president Jimmy Carter was back at work first thing Monday morning after flying home early from South America on Sunday because he was “not feeling well.”

“I have escaped from Guyana because I didn’t want to spread my bad cold all over the country,” Carter, who turned 90 last October, joked at The Carter Center as he welcomed participants in a summit on the global sexual exploitation industry.

He urged the group to “be bold and aggressive” on the problem of human trafficking and assured them that he himself is “fine and getting along well and glad to be back.”

Carter had arrived in Guyana on Friday for the Center’s 100th election-monitoring mission but abruptly headed home on Sunday, leaving his team to carry on in Guyana without him through Monday’s elections there.

“President Carter was not feeling well and has departed Guyana to return to Atlanta today,” the Carter Center said in a statement on Sunday.

Characterizing Carter’s ailment as “nothing serious, just like a cold,” a friend of the former president tells PEOPLE that he is “just fine” and was out walking the expansive Carter Center grounds as soon as he got home on Sunday.