Sahara held grudges.
Normally, Sahara seemed easy-going and played well with many children in the courtyard, but once he set his mind on someone, he would likely hold it for a long time. This was the experience Zheng Tan had gathered over the more than five years he had known Sahara. From the current situation, those few people must have annoyed Sahara somehow.
Many animals have a strong, lasting impression of humans, based not only on appearance but also on voice and scent. Regardless of the type, Sahara had remembered those three individuals.
Zheng Tan was not Sahara and did not understand dog language. He could only try to interpret their intentions through his years of understanding Sahara and the other dogs in the courtyard, based on their behaviors, but he could not know the cause of the incidents. To understand, he had to investigate on his own.