is there a statue of limitations on a power of attorney in the state of California?
Typically, a POA is valid for so long as the grantor is alive or has not revoked it. The actual time frame will very much depend on the language in the POA. It should be reviewed by an attorney before a determination can be made.
There are some older powers of attorney that had a seven year expiration date. That law was changed in the '90s, so you will need to look at the power of attorney to be sure it is under the current laws.