It sounds like it's just a temporary increase spurred on by a couple of temporary factors. Nothing to get all worried about. Not like $5/gallon is likely anytime soon.
On the positive side: one expert predicts that gas prices will spike in the next week before gradually decreasing.
https://ktla.com/2019/04/17/california-gas-prices-hit-average-of-4-highest-in-the-state-since-2014/