I got one of those a couple of years ago - for a car that was still mine, I had all the documentation in order and the car was parked outside my house at the time. DVLA are certainly not infallible!
I have signed the petition, though not because I think that renewing a SORN is a dreadful chore, but because I think that the penalty for not renewing is excessive for the gravity of the "crime".
Jim