I think Sona has been affected by the hypothermia and her brain isn't functioning properly and that is what I think caused her to have a case of slight amnesia. Let's see what we have in store for us in tomorrow's episode.
Had it been a typical daily soap, they would have made her unconscious while Rohit would have been crying over her trying to wake her up and after waking up would have a total amnesia forgetting only thay phase when she met Rohitš¤£. We would have seen Rohit pining for her even though they were just friends beforeš.
I hope we get some sensible reason for their conversation.