If you look a bit below that particular section of the penal code, it gives this disclaimer:
851.8.
( l ) For arrests occurring on or after January 1, 1981, and for accusatory pleadings filed on or after January 1, 1981, petitions for relief under this section may be filed up to two years from the date of the arrest or filing of the accusatory pleading, whichever is later. Until January 1, 1983, petitioners can file for relief under this section for arrests which occurred or accusatory pleadings which were filed up to five years prior to the effective date of the statute. Any time restrictions on filing for relief under this section may be waived upon a showing of good cause by the petitioner and in the absence of prejudice.

