BBC writes that Contagious yawn ’sign of empathy’.

Yawning may reveal more about a person than their boredom threshold, according to research. A susceptibility to contagious yawning may actually be a sign of a high-level of social empathy.

“We believe that contagious yawning indicates empathy. It indicates an appreciation of other people’s behavioural and physiological state,” she added.

In other words, when people around you start yawning it is a good thing, it does not have to indicate boredom or being tired.