If I pay my mortgage and get "current" with my lender can they still foreclose on me?

We were being threatened with foreclosure but have since paid our house up and our account is now current. Can the bank still foreclose on us? A friend of mine told me that happened to him and after paying whatever was owed to bring him up to date, the bank still foreclosed on him. Can banks really do that? How is that legal if you've paid your debt to stop the foreclosure? I know state laws are different. We're in California and so is our friend who recently lost his house.