Meher's Birthday

All this while we've seen Iqbal perfectly remembering even the tiniest and most insignificant details about Sameer's life and childhood (Main patang nahin udata tha, tu udati thi!) and so on. Details that don't really seem possible to be acquired in just 6 months?

And then he goes ahead and forgets Meher's birthday. It's such a big event, I just can't fathom how such a perfect soldier could undergo such a lapse of memory... Or maybe he's really Sameer and he truly truly forgot her birthday?? That might explain why he brought them all to the movies (that's where she wanted to go!).

I could just be forcing myself on this post, but the question still remains open-ended...