They probably continued to have California tax withheld in 2024.  Which means, filing a 540NR to get a refund.  I did that for a client a few years ago, and being a nice guy I didn't charge them for it.  I told them to tell the state to stop withholding tax, but they had better things to do in retirement.  So the next year I did another 540NR, and FTB sent them a bill for penalty owed because the box was not checked to indicate they have health insurance.  Thankfully, they are no longer clients.