Some states adopt a different Standard Deduction than the federal Standard Deduction. This year, the federal Standard Deduction was nearly doubled by the Tax Cut and Jobs Act of 2017, but many states did not increase their standard deductions.
In this case, it is not uncommon for your itemized deductions to be less than the threshhold for the Standard Deduction on the federal return (so no Schedule A needed), but more than the Standard Deduction for your state, so the state's Schedule A (if one) is used.
See
https://www.ftb.ca.gov/individuals/faq/net/902.shtml for California's Standard Deduction for 2018.
