Flags of several countries were kept as markers for the leaders to take their positions for the group photo at the end of the summit at the Mexican resort city of Los Cabos.
Sandwiched between United States President Barack Obama and his Mexican counterpart, Felipe Calderon, Hu was seen bending down and picking up the small flag at the end of event, while Obama and German Chancellor Angela Merkel who were standing behind the Chinese leaders watched with curiosity.
"After posing for the family photo, all the leaders walked off the stage stepping on the national flags. Only Chinese President Hu Jintao bent down to pick up the Chinese national flag and carefully conserved it," the ruling Communist Party of China's official mouthpiece People's Daily said.
The Daily's website carried different frames of 70-year-old Hu, also the general secretary of the ruling Communist party, bending down and picking up the flag.
"This little detail was highly praised by netizens, who expressed their respect to the Chinese president," it said.
"The Chinese national flag represents the dignity of China which in no way should be violated. President Hu preserved the honour of China by his actions, setting a good example for the people all over the country," it quoted netizen commented.
"I am deeply touched and proud of being a Chinese," another netizen said.