In the first episode, Adi and Zoya wished Pooja happy birthday and Yash marriage anniversary simultaneously, so I think Pooja's birthday and ZoSh's anniversary fall on the exact same day...may be Zoya was so much taken aback when Adi said he used Pooja'a birthdate that she didn't even realize it was their anniversary date as well...I don't think CVs would forget such big detail which was emphasized so much in the first episode...let's give them some time to slowly unfold their story!!