Do I have to pay CA state income tax on stock options' proceeds (Non-Qual Stock Options Plan from CA employer) if I live in FL?

On the last quarter of 2015 I retired and moved from CA to FL (still live in FL). I received a W2 from my previous employer reflecting the proceeds from stock options I exercised during 2016. This W2 shows Fed. Inc. Tax withheld as well as CA's state income tax. I'm curious about why the latter and if there is any way to get CA's taxes reimbursed. Thanks.