There is a giggle by Shreya Ghoshal at the end of the song. Shreya has an account on twitter (which she visits pretty much every day), and I asked here about it; her response -
"Hey! The giggle wasn't, the sargam was RT @Rivjot: @shreyaghoshal there is a giggle &short sargam in the end of 'Aaj Dil'-was it intentional" Another unconventional sound like many other Rahman songs :)
