My manager got upset when I told her about my leave

So there are delhi elections taking place on Feb 5 and my company has asked all the employees who are eligible to vote in these elections can take a leave without marking it on the workday.

So in one of my 1:1 meetings i told my manager that I would be on leave on 5 feb and the moment I said this there was visible frustration on her face. It was as if I had asked for leaves from her kitty.