Power Steering Fault II

On my way to work, I turned a corner and the power steering fault light came up.  I was not happy.  The power steering was faulty about a year ago, and I could not believe it was happening.  I kept driving down, and contemplating contacting the garage last repaired it, or calling AA again.  Then just before I turn into work, the fault light went off and it was operating normally again.  I could not work out what caused it, let's hope it doesn't play up again!