Irrfan Khan seems to be on a quest of perfectionism. He locked lips with Dia Mirza when the script only said that he should give his co-star a peck on the cheek.
Perhaps he felt that the chemistry between the two characters demanded such measures.
According to sources, the shoot was on in South Africa. In the scene, Dia introduces Irrfan to Fardeen Khan and Irrfan comes forward to kiss Dia on the cheek and make it clear to Fardeen to not enter into his territory.
He does this because he suspects something is going on between Fardeen and Dia. However, everyone was surprised when Irrfan suddenly kissed Dia on the lips.
It was unexpected, not being a part of the script, but she chose not to make an issue out of it at that time and simply called up Sanjay later on.
Dia admits that she was surprised by the kiss gone wrong, but she thinks that Irrfan did it to establish the chemistry between them in the scene.
Nice excuse to get intimate with a hottie dude!