I'm in the same boat. My CA license just expired on Feb. 5, and I won't be in California until the end of March. I'll admit to fretting about it, but I let it expire for a few reasons.
1) I don't really need it since I can drive on my UK license (which I got exactly one week before my CA license expired!).
2) It's yet another factor in favor of my not being liable for CA income tax - the state that tries to tax anyone who doesn't move past the state fast enough.
3) I'm pretty sure (not positive, admittedly) it's not legal to have a CA license when you don't live there.
Besides an emotional tie (I've had a CA license my entire adult life!), the idea of having to take the test again was probably the most worrisome aspect (particularly after struggling so much with the UK test!), but it's unlikely that I'll need to get another CA driver's license anyway. Not to mention, after finally passing the UK test I feel rather invincible - the CA driver's test should be a piece of cake after that one!
Have I mentioned recently that I passed my UK driver's test?