The U.S. Secret Service takes weeks sometimes to map out and clear routes for the President to travel. that’s even if it’s home or abroad. So you can imagine how tough it is to protect your most important asset when they say “let’s take a walk”.
It’s not the first time Obama has just gone for a walk about.
All former Presidents would walk around to talk to people but they were staged to included a press conference like the video below with President Clinton.