No problem insomuch as any “hi-cap” mags” are “grandfathered” since California has rewrote their Penal Codes and have virtually no way to confirm when they came into your possession. The rub is that any California LE can confiscate any magazine over 10 rounds as a “nuisance item” on a whim and you can get to try to get them back. Good luck with that if you want to hire a lawyer for a $40 magazine.
One of the new laws signed by the Governor makes possession an "infraction"; same as some speeding tickets. First offense is $100 fine. Second is $250, etc. No whims required. Not sure of the effective date. Next July I think.