Eventually she will, because once she gets home, everyone (Asad, included) will want to find out what happened, and who actually poisoned the sweets. Zoya will put two and two together. There are a couple of clues that she has:
1. She only told Tanveer about the annivesary of her Aapi and Jiju
2. She only shared the plan of Ayaan's engagement with Tanveer
3. She only shared her emotional feelings about waiting for Asad with Tanveer.
4. There is a *lady* informer that DB mentioned. He specifically mentioned that it was a female, not just informer.
She will definitely put two and two together when things calm down. Right now, we are (as she is) too busy with the engagement! Ha ha! Dadi already planted a doubt in her mind. And, she was quick to notice also, that Tanveer was the one who told Asad about the anniversary. I am sure, Asad will want to turn detective too.