Something similar happened on the sets of Vishal Bharadwaj's SAAT KHOON MAAF. It's learnt that Priyanka's well toned body didn't make her fit to don the character of a 38 year old lady. When the filmmaker found that Priyanka did not look convincing as a 38 year old lady trying to woo her actor, he had to use a body double for that particular sequence.
The scene was being performed between Priyanka and Vivaan Shah (Naseeruddin Shah's son). Well, looks like being too fit can go against you at times.