As Modi finished his extempore speech, delivered in Hindi, which the members of parliament including the Bhutanese prime minister Tshering Tobgay and other important dignitaries listened to in rapt attention with the help of interpreters, the gathering broke into spontaneous applause.
The clappings began in one corner of the national assembly - the lower house where the joint session was held - and it soon spread among the VVIPs seated at the chamber, as also the visitors' gallery where a large number of Indian and Bhutanese journalists and other officials as also some meritorious students were present.
As the applause reverberated from almost all corners of the assembly, some of their countrymen smiled embarrassed.
In fact, an advisory issued to the media on Sunday itself had refered to the custom. "It may kindly be noted that there will be no clappings/applause in the Bhutanese Parliament during the prime minister's address to the joint session of the Bhutanese Parliament.
"This is because of the Bhutanese religious belief that clapping is done only to ward off evil spirit," said the notice posted at the media centre set up here for Modi's two-day trip.