If I live in SC and work as an adjunct professor online for a CA college, do I need to file a nonresident tax return with CA? I only made $465 last year from them!

No, a remote worker that does not physically work in California (CA) is not taxed on the income earned as a remote worker.  You file the income on your resident state.

The following are states that do tax remote workers at this time.

Income is derived from the employer's workplace regardless of where the employee physically performed the work. 

Exception: The employee is working in the other state due to requirements of the job or work.

States that use this rule are:

Arkansas

Delaware

Nebraska

New York 

Pennsylvania

Connecticut - if the employee resides in a state that follows this rule.